This invention relates generally to novel hindered amine light stabilizers (HALS) and their use as a protectant against ultraviolet radiation or light (xe2x80x9cUV lightxe2x80x9d). Also included are concentrates and articles including such stabilizers, and methods of making all of the above.
It is well known that ultraviolet (xe2x80x9cUVxe2x80x9d) light or radiation, especially sunlight, can cause degradation of a variety of materials, especially polymeric materials. Often this results in embrittlement or yellowing of the materials, which may be in the form of molded articles, extruded articles, films, tapes, coatings, or the like. However, this degradation can be inhibited by the incorporation of light stabilizers in, or on, the polymeric articles. The most commonly used stabilizers are UV-absorbers, hindered amine light stabilizers (xe2x80x9cHALSxe2x80x9d), and phenolic and non-phenolic antioxidants.
HALS scavenge free radicals formed in polymeric material when the material is exposed to UV light. The functional component of the HALS molecule is typically the 2,2,6,6-tetraalkylpiperidine moiety. Typically, the 2,2,6,6-tetraalkylpiperidine moiety is anchored to a carbonyl or melamine functional group (See, e.g., U.S. Pat. Nos. 4,331,586; 3,840,494; Re. 31,342; Re. 30,385; 3,640,928; 4,086,204; 4,265,805). Anchoring the 2,2,6,6-tetraalkylpiperidine moiety to a carbonyl or melamine functional group typically lowers the volatility and extractability of a stabilizer. Low volatility is an important characteristic of light stabilizers in applications where high temperatures are encountered, which occurs frequently in the processing of thermoplastics and in the curing of thermoset resins and coatings. Often, high temperatures are also present in the end-use applications for the stabilized material. Low volatility helps prevent loss of the stabilizer during processing, curing, and high temperature end uses. Typically, HALS molecules containing the 2,2,6,6-tetraalkylpiperidine group anchored to a carbonyl group are made by reacting a 2,2,6,6-tetraalkylpiperidin-4-ol or 4-amino-2,2,6,6-tetramethylpiperidine with a carboxylic acid chloride or ester.
U.S. Pat. Nos. Re. 31,342, 4,021,432 and 4,049,647 disclose a class of 1- and 4-substituted piperidines that are stabilizers for organic materials. The stabilizers are produced by reacting the corresponding 1-substituted piperidinols with acid chlorides, or the corresponding 4-substituted piperidines, with a compound introducing a residue into the 1-position of the piperidine moiety.
U.S. Pat. No. 3,840,494 discloses a polymer composition stabilized against photo- and thermal deterioration by incorporating therein acid esters of 4-piperidinol derivatives in an amount sufficient to prevent such deterioration. The acid esters of the 4-piperidinol derivatives are prepared by reacting the 4-piperidinol derivative with a carboxylate ester in xylene with sodium hydroxide. For example, the reaction of 4-hydroxy-2,2,6,6-tetramethylpiperidine with ethyl benzoate produces 4-benzoyloxy-2,2,6,6-tetramethylpiperidine.
Similarly, the 2,2,6,6-tetramethylpiperidin-4-ol can be reacted with diesters or diacid chlorides to produce diester-HALS. Also, the 2,2,6,6-tetramethylpiperidin-4-ol can be reacted with a diisocyanate to produce a diurethane-HALS. However, the relatively high cost of diisocyanates makes them less practical than diesters when preparing HALS.
Compounds which have an ester functionality at one terminus of a hydrocarbon chain and a urethane functionality at the other terminus of the hydrocarbon chain (alkoxycarbonylamino alkanoates) are known for various other uses other than light stabilization and can be prepared by a variety of synthetic schemes (See, e.g., Effenberger, F.; Drauz, K.; Foerster, S.; Mueller, W., Chem. Ber., 114(1), 173-89; Dixit, A.; Tandel, S.; Rajappa, S.; Tett. Lett.; 35(33), 6133-4, Duong, et al., Aust. J. Chem., 29, 2651-61, 1976; Iwaka et al., J. Org. Chem., 31, 142-46, 1966; Taub; Hino; J. Chem. Eng. Data, 9, 106, 1964; U.S. Pat. No. 5,300,678 to Merger et al.).
Oligomeric HALS are also known. For example, TINUVIN 622 is a commercially available oligomeric HALS produced by Ciba Specialty Chemicals Inc. of Hawthorne, N.Y. TINUVIN 622 can be produced by the reaction of dimethyl succinate with N-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-piperidinol. U.S. Pat. No. 4,223,412 discloses condensation and addition polymers wherein the recurrent molecular unit contains a polyalkylpiperidine radical that are useful as light stabilizers for plastics. In one embodiment the copolymer is formed by copolymerization or copolycondensation of polyalkylpiperidine containing monomers with polyalkylpiperidine free monomers such as caprolactam.
U.S. Pat. No. 4,331,586 to Hardy discloses oligomers that contain at least one piperidyl moiety in the repeating unit for use as light stabilizers. While providing protection for polymeric materials, such as polypropylene, polymeric films containing the disclosed oligomeric HALS became brittle after exposure to UV light for about 1,700 hours.
HALS compounds may be used individually or in combination with other light stabilizers to inhibit photodegradation of polymers. For example, UV light absorbers, such as benzotriazoles and benzophenones, were initially used to stabilize polymeric materials and to prevent degradation of such materials from exposure to UV light. Later, it was discovered that HALS compounds were more effective than UV light absorbers alone, and thus, UV light absorbers are presently used in combination with at least one HALS compound in most conventional applications (See, e.g., U.S. Pat. Nos. 4,740,542; 4,619,956; 5,461,151; 5,721,298). Similarly, HALS compounds are often employed in combination with other stabilizers, such as antioxidants (See, e.g., U.S. Pat. No. 4,722,806). Combining the HALS with another stabilizer may provide a polymeric material with better resistance to weathering.
U.S. Pat. No. 4,619,956 discloses a method of stabilizing a polymer film, coating, or molded article against the action of light, moisture and oxygen by incorporating a HALS compound and a tris-aryl-s-triazine UV light absorber into a polymer. Preferably, the HALS compound is a 2,2,6,6-tetraalkylpiperidine compound, salt, or metal complex, and the UV light absorber is a tris-aryl-2-triazine of formula 
where X, Y, and Z are each aromatic carbocyclic groups, and at least one of the aromatic groups has a hydroxy group ortho to the point of attachment to the triazine ring. Each of R1 to R9 is hydrogen, hydroxy, alkyl, alkoxy, sulfonic, carboxy, halo, haloalkyl, or acylamino. Each of the UV light absorbers and HALS compound are used in an amount of from about 0.01 to 5 percent by weight, but only formulations having equal amounts of UV light absorber and HALS compound are exemplified. The compositions are effective in stabilizing the polymeric material, which does not begin to lose gloss or turn yellow until after about 1,000 to 2,400 hours of exposure to UV light.
Thus, a need still remains for improved articles, and compositions and methods of use and preparation thereof, that stabilize polymeric materials and provide protection from exposure to UV light for extended periods of time. The present invention provides such compositions, articles and methods.
The invention provides a new class of oligomeric HALS having the formula:
T"Parenopenst"Exe2x80x94F"Parenclosest"i"Parenopenst"Exe2x80x94Fxe2x80x2"Parenclosest"j"Parenopenst"Exe2x80x2xe2x80x94F"Parenclosest"k"Parenopenst"Exe2x80x2xe2x80x94Fxe2x80x2"Parenclosest"lSxe2x80x83xe2x80x83(II)
wherein i, j, k, and I are integers from about 0 to 300 and the sum of i, j, k, and 1 is greater than 2, wherein T is F, Fxe2x80x2, or hydrogen; S is E, Exe2x80x2, or hydrogen;
Exe2x80x94F is 
S is a hydrogen, or a unit derived from a piperidin-4-ol or a 4-aminopiperidine moiety having the structure 
and T is a hydrogen or a unit derived from a multi-functional carbonyl compound having the structure 
wherein D is a hydrocarbyl group, n is an integer from 1 to 15, m is either 0 or 1, s is 0 or an integer from 1 to 10; Ra, Rb, Rc, and Rd, are each a hydrogen or a hydrocarbyl group; Y is COxe2x80x94(CReRf)p, wherein Re and Rf are each a hydrogen or hydrocarbyl group and p is an integer from 0 to 20 or COxe2x80x94C6H4xe2x80x94, wherein the substitution pattern on the phenylene group is an ortho, meta, or para substitution pattern, and one or more of the hydrogens of the phenylene group may be substituted by a hydrocarbyl group or a functional group; R2 is hydrogen, C1-C8 alkyl, or benzyl; R3, R4, R5, and R6 are each a hydrogen, C1-C8 alkyl, benzyl or phenethyl, or two geminal R moieties, which together with the carbon to which they are attached form a C5-C10 cycloalkyl; Z is xe2x80x94Oxe2x80x94 or NG, wherein G is H or C1-C12 alkyl; and P is NH or O.
The sum of i, j, k, and l may be greater than 6. In one embodiment R2 is H, or C1-C4 alkyl; R3, R4, R5, and R6 are each H or C1-C4 alkyl; Ra, Rb, Rc, and Rd are each a hydrogen, aromatic, or C1-C4 alkyl; n is from 4 to 11; and s is from 2 to 5. In another embodiment R2, R3, R4, R5, and R6 are each a hydrogen; Ra, Rb, Rc, and Rd are each a hydrogen, Z is O, n is from 4 to 11, and s is 2. The average molecular weight may be from about 400 to 20,000.
The invention also provides for a method of preparing the oligomeric HALS of the invention. The method involves combining one or more multi-functional carbonyl compounds of general structure
DOxe2x80x94COxe2x80x94CRaRbxe2x80x94(xe2x80x94CRcRdxe2x80x94)nxe2x80x94NHxe2x80x94(Y)mxe2x80x94COxe2x80x94ODxe2x80x83xe2x80x83(IV)
wherein n is an integer from 1 to 15, m is either 0 or 1; Ra, Rb, Rc, and Rd, are each a hydrogen or a hydrocarbyl group; Y is COxe2x80x94(CReRf)p, wherein Re and Rf are each a hydrogen or hydrocarbyl group and p is zero or an integer from 1 to 20 or COxe2x80x94C6H4xe2x80x94, wherein the substitution pattern on the phenylene group is an ortho, meta, or para substitution pattern, and one or more of the hydrogens of the phenylene group may be substituted by a hydrocarbyl group or a functional group; and D is a hydrocarbyl group with one or more 1-substituted piperidin-4-ol or 4-aminopiperidines of general structure 
wherein Z is OH or NHG, wherein G is H or C1-C12 alkyl, R1 is xe2x80x94(CH2)sxe2x80x94OH or xe2x80x94(CH2)sxe2x80x94NH2, wherein s is an integer from 1 to 10; R2 represents hydrogen, C1-C8 alkyl, or benzyl; R3, R4, R5, and R6 are each a hydrogen, C1-C8 alkyl, benzyl or phenethyl, or two geminal R moieties, which together with the carbon to which they are attached form a C5-C10 cycloalkyl, to provide a reaction mixture; reacting the reaction mixture for a sufficient time to form the compound of formula (II); and recovering the compound of formula (II) from the reaction mixture.
The reaction mixture may include a solvent. The solvent may be one or more of benzene, toluene, or one or more xylenes. The one or more multi-functional carbonyl compounds may be present in an amount of from about 0.025 M to 2.5 M. The molar ratio of the one or more multi-functional carbonyl compounds to the one or more 1-substituted piperidin-4-ol or 4-aminopiperidines may be from about 5:1 to 1:5. In one embodiment R1 is xe2x80x94(CH2)2OH; R3, R4, R5, and R6 are each CH3; and R2 is H; Ra, Rb, Rc and Rd are each hydrogen; Z is xe2x80x94Oxe2x80x94, and n is 4, and D is CH3.
The reaction mixture may also include a catalyst. The catalyst may be a base or an acid. When the catalyst is an acid it may be a Lewis acid selected from the group consisting of aluminum trichloride, aluminum tribromide, trimethylaluminum, boron trifluoride, boron trichloride, 1,3-diacetoxy-1,1,3,3-tetrabutyldistannoxane, zinc dichloride, titanium tetrachloride, titanium (IV) isopropoxide, tin dichloride, tin tetrachloride, a tetraalkoxytitanate, or mixtures thereof. The catalyst may be present in an amount of less than about 30 mole percent based on the molar quantity of the multi-functional carbonyl compound.
In another embodiment the oligomeric HALS is prepared in a single step by combining one or more lactams of general structure 
wherein n is an integer from 1 to 15 and Ra, Rb, Rc, and Rd are each a hydrogen or a hydrocarbyl group with one or more carbonyl compounds of general structure 
wherein m is either 0 or 1, D is a hydrocarbyl group, B is a hydrocarbyl group or OD, and Y is COxe2x80x94(CReRf)p, wherein Re and Rf are each a hydrogen or hydrocarbyl group and p is an integer from 0 to 20 or COxe2x80x94C6H4xe2x80x94, and the substitution pattern on the phenylene group may be an ortho, meta, or para substitution pattern, and one or more of the hydrogens of the phenylene group may be substituted by a hydrocarbyl group or other functional group; and one or more 1-substituted piperidin-4-ol or 4-aminopiperidines of general structure 
wherein Z is OH or NHG, wherein G is H or C1-C12 alkyl, R1 is xe2x80x94(CH2)sxe2x80x94OH or xe2x80x94(CH2)sxe2x80x94NH2, wherein s is an integer from 1 to 10; R2 represents hydrogen, C1-C8 alkyl, or benzyl; R3, R4, R5, and R6 are each a hydrogen, C1-C8 alkyl, benzyl or phenethyl, or two geminal R moieties, which together with the carbon to which they are attached form a C5-C10 cycloalkyl to provide a reaction mixture; reacting the reaction mixture for a sufficient time to form the compound of formula (II); and recovering the compound of formula (ID from the reaction mixture.
The carbonyl compound may be a dialkyl carbonate, a dialkyl oxalate, a dialkyl diester, an alkyl ester, or a combination thereof. The reaction mixture may include a catalyst. The catalyst may be present in an amount of less than about 30 mole percent relative to the one or more carbonyl compounds. The catalyst may be a base or a Lewis acid. The Lewis acid may be aluminum trichloride, aluminum tribromide, trimethylaluminum, boron trifluoride, boron trichloride,1,3-diacetoxy-1,1,3,3-tetrabutyldistannoxane, zinc dichloride, titanium tetrachloride, titanium (IV) isopropoxide, tin dichloride, tin tetrachloride, a tetraalkoxytitanate, and mixtures thereof. The reaction may also be carried out in a solvent. The solvent may be one or more of benzene, toluene, or one or more xylenes.
The concentration of the one or more lactams may be from about 0.075 to 10 M. The ratio of the one or more lactams to the one or more carbonyl compounds may be from about 2:1 to 1:4, the ratio of the one or more lactams to the one or more 1-substituted piperidin-4-ol or 4-aminopiperidines may be from about 2:1 to 1:2, and the catalyst may be present in an amount of less than about 30 mole percent relative to the amount of the one or more carbonyl compounds. In one embodiment n is from 3 to 12 and the catalyst is a base catalyst or a Lewis acid. The lactam may be caprolactam or laurolactam.
An improved class of HALS compounds has now been discovered that provides substantially similar or superior UV light protection over a longer period of time compared to conventional HALS compounds. The HALS compounds of the present invention are based on the reaction of a lactam with the carbonyl group of a carbonyl compound. The HALS compounds of the present invention include compounds where the functional component of the HALS compound, a piperidin-4-ol or 4 aminopiperidine group, is anchored to the terminus of a hydrocarbon chain by an ester functionality or an amide functionality and wherein the other end of the hydrocarbon chain terminates with an amide linkage that is not a HALS functionality. These may be referred to as xe2x80x9cester/amide HALS compoundsxe2x80x9d and xe2x80x9camide/amide HALS compounds.xe2x80x9d Alternatively, both ends of the hydrocarbon chain can terminate with the piperidin-4-ol or 4 aminopiperidine group. In this embodiment, the HALS molecule is anchored to one terminus of the hydrocarbon chain by an ester functionality and to the other terminus by a urethane functionality. These may be referred to as xe2x80x9cester/urethane HALS compounds.xe2x80x9d Furthermore, the HALS molecule may be anchored to one terminus of the hydrocarbon chain by an amide functionality and to the other terminus by a urea functionality. These may be referred to as xe2x80x9camide/urea HALS compounds.xe2x80x9d In yet another series of compounds, the piperidin-4-ol or 4 aminopiperidine group is bonded by an ester linkage to one terminus of the hydrocarbon chain and by an oxamate linkage at the other terminus of the hydrocarbon chain to provide xe2x80x9cester/oxamate HALS compounds,xe2x80x9d or the piperidin-4-ol or 4 aminopiperidine group is bonded by an amide linkage to one terminus of the hydrocarbon chain and by an oxamide linkage at the other terminus of the hydrocarbon chain to provide xe2x80x9camide/oxamide HALS compounds.xe2x80x9d
These HALS compounds are represented by the general formula (I)
RZxe2x80x94COxe2x80x94CRaRbxe2x80x94(xe2x80x94CRcRdxe2x80x94)nxe2x80x94NHxe2x80x94(Y)mxe2x80x94COxe2x80x94Axe2x80x83xe2x80x83(I)
wherein n is an integer from 1 to 15, preferably 4 to 11; m is either 0 or 1; Ra, Rb, Rc, and Rd, are each a hydrogen or a hydrocarbyl group; Y is COxe2x80x94(CReRf)p, wherein Re and Rf are each a hydrogen or hydrocarbyl group and p is zero or an integer from 1 to 20 or COxe2x80x94C6H4xe2x80x94, and the substitution pattern on the phenylene group, i.e., xe2x80x94C6H4xe2x80x94, may be an ortho, meta, or para substitution pattern, in addition one or more of the hydrogens of the phenylene group may be substituted by a hydrocarbyl group or other functional group commonly found in organic molecules; Z is xe2x80x94Oxe2x80x94 or NG, wherein G is H, C1-C12 alkyl or the radical R; wherein the radical R represents: 
wherein R1 represents hydrogen, C1-C18 alkyl, O, OH, CH2CN, C1-C18 alkoxy, C5-C12 cycloalkoxy, C3-C6 alkenyl, C1-C18 alkynyl, C7-C9 phenylalkyl, unsubstituted or substituted on the phenyl with 1, 2 or 3 C1-C4 alkyls, or an aliphatic C1-C18 acyl; R2 is hydrogen, C1-C8 alkyl, or benzyl; R3, R4, R5, and R6 are each a hydrogen, C1-C8 alkyl, benzyl or phenethyl, or two geminal R moieties, which together with the carbon to which they are attached, form a C5-C10 cycloalkyl; and A is either ZR or a hydrocarbyl group.
The term xe2x80x9chydrocarbyl,xe2x80x9d as used herein, is a monovalent hydrocarbon group in which the valency is derived by extraction of a hydrogen from a carbon. Hydrocarbyl includes, for example, aliphatics (straight and branched chain), cycloaliphatics, aromatics and mixed character groups (e.g., aralkyl and alkaryl). Hydrocarbyl also includes groups with internal unsaturation and activated unsaturation. More specifically, hydrocarbyl includes, but is not limited to, alkyl, cycloalkyl, aryl, aralkyl, alkaryl, alkenyl, cycloalkenyl, and alkynyl, typically having from about 1 to 24 carbon atoms, preferably having from about 1 to 12 carbon atoms. A hydrocarbyl may contain one or more carbonyl groups (which is/are included in the carbon count) and/or a heteroatom or heteroatoms (such as at least one oxygen, nitrogen, sulfur, or silicon) in the chain or ring. In addition, a hydrocarbyl may have one or more of the hydrogens of the hydrocarbon group replaced by a functional group commonly found in organic molecules. The phrase xe2x80x9cfunctional group commonly found in organic moleculesxe2x80x9d means non-hydrocarbyl groups that are typically found in organic molecules including, but not limited to, halides, cyano groups, amino groups, thiol groups, carboxylate groups, hydroxyl groups, sulfonate groups, nitroso groups, nitro groups, and the like.
In a preferred embodiment of the invention, R1 is H, C1-C4 alkyl,C1-C18 alkoxy, C5-C12 cycloalkoxy, O, or OH; R2 is H, or C1-C4 alkyl; R3, R4, R5, and R6 are H or C1-C4 alkyl; Ra, Rb, Rc, and Rd, are each a hydrogen, aromatic, or C1-C4 alkyl; and n is from about 2 to 10. In a more preferred embodiment, R represents the 2,2,6,6-tetramethylpiperidine radical (i.e., R3, R4, R5, R6 are methyl and R2 is hydrogen) or 1,2,2,6,6-pentamethylpiperidine radical (i.e., R2, R3, R4, R5, and R6 are methyl); Ra, Rb, Rc, and Rd are each a hydrogen; Z is xe2x80x94Oxe2x80x94; m is 0 or 1; and n is 4 to 10.
The HALS compounds of the formula (I) are typically prepared by the reaction of a multi-functional carbonyl compound with a 4-piperidin-ol or a 4-aminopiperidine moiety. The multi-functional carbonyl compound has the general structure:
DOxe2x80x94COxe2x80x94CaRbxe2x80x94(xe2x80x94CRcRdxe2x80x94)nxe2x80x94NHxe2x80x94(Y)mxe2x80x94COxe2x80x94B
wherein n is an integer from 1 to 15, preferably 4 to 11; m is either 0 or 1; Ra, Rb, Rc and Rd, are each a hydrogen or a hydrocarbyl group; Y is COxe2x80x94(CReRf)p, wherein Re and Rf are each a hydrogen or hydrocarbyl group, and p is zero or an integer from about 1 to 20 or COxe2x80x94C6H4xe2x80x94, and the substitution pattern on the phenylene group, i.e., xe2x80x94C6H4xe2x80x94, is an ortho, meta, or para substitution pattern, in addition one or more of the hydrogens of the phenylene group may be substituted by a hydrocarbyl group or a functional group commonly found in organic molecules; D is a hydrocarbyl group; and B is either OD or D; and reacting the carbonyl compound with a 1-substituted piperidin-4-ol or 4-aminopiperidine of general structure: 
wherein Z is OH or NHG, wherein G is H or C1-C12 alkyl or the radical R (wherein R is defined above); and R1 represents hydrogen, C1-C18 alkyl, O, OH, CH2CN, C1-C18 alkoxy, C5-C12 cycloalkoxy, C3-C6 alkenyl, C1C18 alkynyl, C7-C9 phenylalkyl, unsubstituted or substituted on the phenyl with 1, 2 or 3 C1-C4 alkyls, or an aliphatic C1-C8, acyl; R2 is hydrogen, C1-C8 alkyl, or benzyl; R3, R4, R5, and R6 are each a hydrogen, C1-C8 alkyl, benzyl or phenethyl, or two geminal R moieties, which together with the carbon to which they are attached, to form a C5-C10 cycloalkyl.
The reaction between the multi-functional carbonyl compound and the 4-piperidin-ol or 4-aminopiperidine moiety is conducted for a sufficient time for the compound of formula (I) to be formed. The phrase xe2x80x9cconducted for a sufficient time for the compound of [a given formula] to be formedxe2x80x9d means that after the reactants are combined they are allowed to react for sufficient time to produce a detectable amount of the desired compound, i.e., the compound of a given formula. By xe2x80x9cdetectable amountxe2x80x9d of a compound is meant an amount of the compound that can be detected by any means readily available to those of ordinary skill in the art. Means for detecting the formation of a compound in a reaction mixture include, but are not limited to, thin layer chromatography (TLC), high performance liquid chromatography (HPLC), gas chromatography (GC), column chromatography, nuclear magnetic resonance spectroscopy (NMR), infra-red (IR) spectroscopy, ultra-violet (UV) or visible (VIS) spectroscopy, and wet-chemical analysis, for example. The length of time for the desired compound to be produced is dependent on a number of variables and, thus, cannot be generalized. For example, the reaction time is dependent on the temperature, the pressure, the specific reactants (i.e., the multi-functional carbonyl compound and the 1-substituted piperidin-4-ol or 4-aminopiperidine), and the solvent and catalyst, if present. Acceptable parameters that produce the desired product, however, may be readily determined by those of ordinary skill in the art without undue experimentation.
The reaction may be carried out in the absence of a solvent or in the presence of a solvent. When the reaction is carried out in the absence of a solvent either the multi-functional carbonyl compound or the 4-piperidin-ol or 4-aminopiperidine may be present in an excess and employed as the reaction medium. Alternatively, the multi-functional carbonyl compound and 4-piperidin-ol or 4-aminopiperidine can be present in a stoichiometric amount. The multi-functional carbonyl compound and 4-piperidin-ol or 4-aminopiperidine may be present in a melt. Preferably, the reaction is carried out in an organic solvent. Any solvent compatible with the reagents may be used. Preferred solvents for use in the method of the invention include, but are not limited to, hydrocarbon solvents such as a saturated alkanes; benzene; toluene; xylenes; halogenated hydrocarbons; ethers such as ethyl ether; cyclic ethers such as tetrahydrofuran and dioxane; amides such as dimethylformamide; sulfoxides such as dimethylsulfoxide; ketones such as 2-butanone or methyl isobutyl ketone; and the like; or combinations thereof. The more preferred solvents include toluene, benzene, and xylenes.
When the reaction is carried out in a solvent the concentration of the multi-functional carbonyl in the organic solvent is generally from about 0.025 M to 2.5 M, preferably from about 0.125 M to 2 M, and more preferably from about 0.25 M to 1.35 M. The molar ratio of the 1-substituted piperidin-4-ol or 4-aminopiperidine to the multi-functional carbonyl compound is between about 20:1 and 1:5, preferably between about 10:1 and 1:3, and more preferably between about 5:1 and 1:5.
The reaction of the multi-functional carbonyl compound and 4-piperidin-ol or 4-aminopiperidine produces an alcohol of structure DOH. Preferably, the alcohol is removed from the reaction mixture as it is formed to help drive the reaction to completion. The alcohol may be removed by any means available to those of ordinary skill in the art such as distillation and or azeotropic distillation.
Preferably, the reaction is conducted in the presence of a catalyst. The optional catalyst may be a basic or an acidic catalyst. The phrase xe2x80x9cbase catalystxe2x80x9d means any compound that can abstract a proton. Base catalysts suitable for the invention include, but are not limited to, alkoxide ions; hydroxide ion; amide ion; and amines such as triethylamine, DBU (1,8-diazabicyclo [5.4.0] undec-7-ene), or DBN (1,5-diazabicyclo [4.3.0] non-5-ene). When an amine is used as the base, it is preferred that the amine is a tertiary amine.
The phrase xe2x80x9cacid catalystxe2x80x9d means any inorganic or organic acid with at least one acidic proton or a Lewis acid. The organic acids include any organic compound that contains at least one acidic functional group, including one or more of RCO2H, RSO3H, RSO2H, RSH, ROH, RPO3H, RPO2H, wherein R is a hydrocarbyl group. Preferred protic acids include HCl, HBr, HI, HNO3, HNO2, H2S, H2SO4, H3PO4, H2CO3, acetic acid, formic acid, butanoic acid, benzoic acid, phthalic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, methanesulfonic acid, and p-toluenesulfonic acid, or mixtures thereof Lewis acids suitable for the method of the invention include, but are not limited to, aluminum halides, alkylaluminum halides, boron halides, dialkyl tin oxides and derivatives thereof, tin halides, titanium halides, lead halides, zinc halides, iron halides, gallium halides, arsenic halide, copper halides, cadmium halides, mercury halides, antimony halides, and the like. Preferred Lewis acids include aluminum trichloride, aluminum tribromide, 1,3,-diacetoxy-1,1,3,3-tetrabutyldistannoxane, trimethylaluminum, boron trifluoride, boron trichloride, zinc dichloride, titanium tetrachloride, titanium (IV) isopropoxide, tin dichloride, tin tetrachloride, a tetraalkoxytitanate or a mixture thereof.
The acid or base catalyst may also be a solid supported catalyst such as amberlyst catalysts.
The catalyst is typically added in an amount of less than about 30 mole percent based on the molar quantity of the multi-functional carbonyl compound, preferably less than about 20 mole percent based on the molar quantity of the multi-functional carbonyl compound, more preferably less than about 10 mole percent based on the molar quantity of the multi-functional carbonyl compound, and most preferably less than about 5 mole percent by weight based on the weight of the multi-functional carbonyl compound.
The preferred base catalyst for use in the method of the invention is methoxide ion. The preferred acid catalyst is a Lewis acid. The preferred Lewis acid is 1,3-diacetoxy-1,1,3,3-tetrabutyldistannoxane.
Preferably, the reaction is allowed to proceed for a time that is less than about 20 hours and more preferably less than about 10 hours. Typically, the reaction temperature is from about room temperature to 150xc2x0 C., for example, up to the boiling point of the solvent. Typically, the reactions are run at atmospheric pressure. Representative reaction conditions for forming the compound of formula (I) are provided in the examples.
After the compound of formula (I) is formed, it is recovered from the reaction mixture by any means available to those of ordinary skill in the art. Methods for recovering compounds from a reaction mixture include, but are not limited to, chromatography, recrystallization, distillation, extraction, and the like. More than one method may be used to recover a compound from the reaction mixture.
In a preferred embodiment, the substituted 4-piperidin-4-ol is 1,2,2,6,6-pentamethyl-4-piperidinol or 2,2,6,6-tetramethyl-4-piperidinol and the multi-functional carbonyl compound is methyl 6-(methoxycarbonylamino)hexanoate, butyl 6-(butoxycarbonylamino) undecanoate, methyl 6-(butoxycarbonylamino)undecanoate, butyl 6-(methoxycarbonylamino)undecanoate, or methyl 6-(methoxycarbonylamino)undecanoate.
The multi-functional carbonyl compounds can be prepared by any method available to those of ordinary skill in the art. In one embodiment, the multi-functional carbonyl compound is prepared by reacting a lactam with a carbonyl compound. For example, the multi-functional carbonyl compound can be prepared by the base catalyzed reaction of a lactam and a carbonyl compound according to the method disclosed in U.S. Pat. No. 5,300,678, the contents of which are expressly incorporated herein by reference thereto.
Any lactam may be used according to the method of the invention. Preferably the size of the lactam ring is from about 4 to 13 atoms. More preferably the lactam is caprolactam or laurolactam.
The carbonyl compound must include at least one reactive carbonyl group. xe2x80x9cReactive carbonyl groupxe2x80x9d means any carbonyl group that is attached to a good leaving group and, thus, is activated towards nucleophilic acyl substitution. The reactive carbonyl group may be, for example, an ester or acid chloride. Preferably the carbonyl compound is an ester. More preferred carbonyl compounds include dialkyl carbonates, dialkyl oxalates, dialkyl diesters, or alkyl esters. The general structure of the carbonyl compound is 
wherein m is either 0 or 1, Q is a good leaving group, such as chloride or OD, wherein D is a hydrocarbyl group, preferably methyl, and B is Q or a hydrocarbyl group and Y is COxe2x80x94(CReRf)p, wherein Re and Rf are each a hydrogen or hydrocarbyl group and p is zero or an integer from about 1 to 20 or COxe2x80x94C6H4xe2x80x94, and the substitution pattern on the phenylene group, i.e., xe2x80x94C6H4xe2x80x94, may be an ortho, meta, or para substitution pattern, in addition one or more of the hydrogens of the phenylene group may be substituted by a hydrocarbyl group or other functional group commonly found in organic molecules.
When the carbonyl compound is a dialkyl carbonate, the resulting multi-functional carbonyl compound is a hydrocarbon chain that terminates on one end with an ester functionality and the other end with a urethane functionality. When the carbonyl compound is a dialkyl oxalate, the resulting multi-functional carbonyl compound is a hydrocarbon chain that terminates on one end with an ester functionality and the other end with an oxamate functionality. When the carbonyl compound is a dialkyl ester, the resulting multi-functional carbonyl compound is a hydrocarbon chain that includes an amide linkage and terminates on each end with an ester functionality. When the carbonyl compound is an alkyl ester, the resulting multi-functional carbonyl compound is a hydrocarbon chain that terminates on one end with an ester functionality and the other end with an amide functionality.
The reaction of the lactam with the carbonyl compound can be conducted in a solvent or in the absence of a solvent. When the reaction is conducted in the absence of a solvent, excess carbonyl compound may be employed as the reaction medium and, thus, the carbonyl compound may be present in an excess compared to the lactam. The lactam, however, may also be present in an excess and employed as the reaction medium. Alternatively, the lactam and carbonyl compound can be present in a stoichiometric amount. The lactam and carbonyl compound may be present in a melt. When the reaction is conducted in the absence of a solvent, the excess carbonyl compound or lactam may be recovered by, for example, distillation and reused. An advantage of not using a solvent is that the problems associated with disposal of waste solvents are avoided.
In another embodiment one or more different lactams are reacted with one or more different carbonyl compounds. For example, two lactam molecules can be reacted with 1 molecule of carbonyl compound.
Solvents suitable for the method of the invention include, but are not limited to, hydrocarbon solvents such as a saturated alkane; benzene; toluene; xylenes; halogenated hydrocarbons; ethers such as ethyl ether; cyclic ethers such as tetrahydrofuran and dioxane; amides such as dimethylformamide; sulfoxides such as dimethylsulfoxide; ketones such as 2-butanone or methyl isobutyl ketone; alcohols; and the like; or mixtures thereof. When the reaction is carried out in a solvent the concentration of the lactam in the solvent is from about 0.025 M to 10 M, preferably from about 0.375 M to 6 M, and more preferably from about 0.25 M to 4 M. The mole ratio of lactam to carbonyl compound is typically from about 1:10 to 5:1, preferably from about 1:5 to 2:1, and more preferably from about 1:2.5 to 1.5:1.
The reaction is allowed to proceed for a sufficient time to form a detectable amount of the multi-functional carbonyl compound. In general the reaction time is less than about 12 hours. Typically, the reaction temperature is from about room temperature to 150xc2x0 C., for example, up to the boiling point of the solvent, when a solvent is used. The reaction is typically conducted at room temperature.
The present invention also provides an improved method for preparing the multi-functional carbonyl compound. According to the method of the invention the lactam and a carbonyl compound are reacted in the presence of an acid catalyst, preferably a Lewis acid catalyst.
Any Lewis acid catalyst can be used according to the method of the invention. For example, any of the above-mentioned Lewis acid catalysts may be used. Preferably the Lewis acid catalyst is titanium (IV) isopropoxide. Lewis acids are a preferred catalyst since they can be easily removed from the reaction mixture. For example, many Lewis acids, such as tetraorganotitanates, can be readily hydrolyzed with a stoichometric amount of water, leading to a highly insoluble titanium dioxide that can easily be removed from the reaction mixture by filtration. Other Lewis acids, such as, for example, boron trifluoride etherate, are sufficiently volatile that they can easily be removed from the reaction mixture by distillation. Thus, using a Lewis acid can advantageously avoid having to extract the reaction mixture with an aqueous solvent to remove the catalyst. By avoiding an extraction step to remove the catalyst, the method of the invention generates less aqueous waste that ultimately has to be disposed of.
In another improved method of the invention, the lactam and carbonyl compound are allowed to react with an alkoxide anion as a basic catalyst, preferably methoxide anion. The reaction, however, is conducted at a temperature of less than about 20xc2x0 C., preferably less than about 19xc2x0 C., and more preferably less than about 15xc2x0 C. The lactam and carbonyl compound are allowed to react for less than about 5 hours, preferably less than about 2 hours, and more preferably less than about 1 hour. Conducting the reaction at a low temperature is preferred since temperatures can be kept below the flash point of many reagents and, thus, such low temperature reactions can be significantly safer. For example, dimethyl carbonate (which is a common carbonyl compound for use in the method of the invention) has a flash point of 19xc2x0 C. By running the reaction at a temperature below 19xc2x0 C., i.e., below the flash point, the method is significantly safer than prior art methods that require higher temperatures.
When the multi-functional carbonyl compound is formed, it can be recovered from the reaction mixture before it is reacted with the 1-substituted piperidin-4-ol or 4-aminopiperidine to form the HALS of the invention. The multi-functional carbonyl compound may be recovered by any means available to those of ordinary skill in the art. Optionally, the multi-functional carbonyl compound is not recovered from the reaction mixture and instead the 1-substituted piperidin-4-ol or 4-aminopiperidine is added to the reaction mixture after a detectable amount of the multi-functional carbonyl compound is formed. The 1-substituted piperidin-4-ol or 4-aminopiperidine and the multi-functional carbonyl compound can then react to form the HALS of the invention.
In a preferred method, the compound of formula (I) is prepared by reacting the lactam, carbonyl compound, and 1-substituted piperidin-4-ol or 4-aminopiperidine in a single step. The lactam, the carbonyl compound, and the 1-substituted piperidin-4-ol or 4-aminopiperidine are combined and allowed to react at the same time, rather than reacting the lactam and carbonyl compound to form the multi-functional carbonyl compound in a first step and then, in a subsequent step, reacting the multi-functional carbonyl compound with the 1-substituted piperidin-4-ol or 4-aminopiperidine. The lactam, the carbonyl compound, and the 1-substituted piperidin-4-ol or 4-aminopiperidine are combined in a reaction vessel and allowed to react for sufficient time to form a detectable amount of the HALS of formula (I).
The ratio of lactam to carbonyl compound in this embodiment of the method is from about 2:1 to 1:4, preferably from about 1:1 to 1:2; and the ratio of lactam to 1-substituted piperidin-4-ol or 4-aminopiperidine is from about 1:1 to 1:6, preferably from about 1:2 to 1:4.
The single step reaction can be conducted in a solvent or in the absence of a solvent. When a solvent is used, any solvent that is compatible with the reagents may be used. Representative solvents include, but are not limited to, those solvents described above for the reaction of a 1-substituted piperidin-4-ol or 4-aminopiperidine with a multi-functional carbonyl compound. Preferably, the reaction in this embodiment is carried out in the presence of a solvent. When a solvent is employed, the concentration of lactam is typically from about 0.025 M to 10 M, preferably from about 0.325 M to 6 M, and more preferably from about 0.75 M to 4 M.
Preferably, the reaction is carried out in the presence of a catalyst. The same catalysts may be used as were used in the reaction of a 1-substituted piperidin-4-ol or 4-aminopiperidine with a multi-functional carbonyl compound. The catalyst is typically present in an amount of less than about 30 mole percent, preferably less than about 20 mole percent, and more preferably less than about 10 mole percent, and most preferably less than 5 mole percent, relative to the amount of carbonyl compound.
Preferably, the carbonyl compound is an ester, i.e., Q=OD, so that the reaction produces an alcohol of structure HOD. Preferably, the alcohol is removed from the reaction mixture as it is formed to drive the reaction to completion. The alcohol may be removed by any means available to those of ordinary skill in the art, such as distillation and/or azeotropic distillation.
Preferably, the reaction time is less than about 20 hours and more preferably less than about 10 hours. Typically, the reaction temperature is between about room temperature and 250xc2x0 C. Typically, the reactions are run at atmospheric pressure. Representative reaction conditions for forming the HALS of formula (I) by the single step process are provided in the examples. When the HALS of formula (I) is formed it may be recovered from the reaction mixture by any means available to those of ordinary skill in the art.
The invention also includes oligomeric HALS having the general formula (II)
T"Parenopenst"Exe2x80x94F"Parenclosest"i"Parenopenst"Exe2x80x94Fxe2x80x2"Parenclosest"j"Parenopenst"Exe2x80x2xe2x80x94F"Parenclosest"k"Parenopenst"Exe2x80x2xe2x80x94Fxe2x80x2"Parenclosest"lSxe2x80x83xe2x80x83(II)
wherein i, j, k, and I are integers from about 0 to 300, preferably about 0 to 200, and more preferably 0 to about 100. The sum of i, j, k, and 1 is greater than 2, preferably, the sum of i, j, k, and 1 is greater than about 3 and more preferably is greater than about 6. Preferably at least two of i, j, k, and l are 1 or more, or (III)
T"Parenopenst"(Mxe2x80x94F"Parenclosest"i"Parenopenst"Mxe2x80x94Fxe2x80x2"Parenclosest"jMxe2x80x83xe2x80x83(III)
wherein i and j are integers from about 0 to 300, preferably about 0 to 200, and more preferably 0 to about 100. The sum of i and j is greater than 2. Preferably, the sum of i and j is greater than about 3, more preferably greater than about 6. Preferably at least two of i, j, k, and l are equal to or greater than 1.
In formula (II) E and Exe2x80x2 are a piperidin-4-ol or 4-aminopiperidine moiety and F and Fxe2x80x2 are each a moiety derived from a multi-functional carbonyl compound. T can be F, Fxe2x80x2, or hydrogen and S can be E, Exe2x80x2, or hydrogen. Exe2x80x94F includes: 
Exe2x80x94Fxe2x80x2 includes: 
Exe2x80x2xe2x80x94F includes:
and Exe2x80x2xe2x80x94Fxe2x80x2 includes:
In formula (III), M is a diamino or a dihydroxy group that contains the 4-aminopiperidine group, R, as defined above. By xe2x80x9cdiamino or a dihydroxy groupxe2x80x9d is meant a group derived from a compound that contains at least two hydroxy groups, at least two amino groups, or at least one amino group and one hydroxy group. The amino group can be either a primary or secondary amino group.
Mxe2x80x94F includes: 
Mxe2x80x94Fxe2x80x2 includes: 
In the oligomeric HALS of formula (III) the diamino or dihydroxy group that contains the 4-aminopiperidine group, i.e., M, is bonded to the multi-functional carbonyl compound by the hydroxy or amino group.
Formulas II and III may be a block copolymer or a random copolymer, i.e., the units Exe2x80x94F, Exe2x80x94Fxe2x80x2, Exe2x80x2xe2x80x94F, and Exe2x80x2xe2x80x94Fxe2x80x2 or Mxe2x80x94F and Mxe2x80x94Fxe2x80x2 are distributed randomly throughout the polymer chain. In the above oligomeric HALS of structure (II) or (III) S is a hydrogen, or a unit derived from a piperidin-4-ol or a 4-aminopiperidine moiety and has the structure 
and T is a hydrogen or a unit derived from a multi-functional carbonyl compound and has the structure 
wherein D is a hydrocarbyl group.
In the oligomeric HALS of formula (II) and (III) n is an integer from 1 to 15, preferably 4 to 11, m is either 0 or 1, s is 0 or an integer from about 1 to 10; Ra, Rb, Rc, and Rd, are each a hydrogen or a hydrocarbyl group; Y is COxe2x80x94(CReRf)p, wherein Re and Rf are each a hydrogen or hydrocarbyl group and p is zero or an integer from about 1 to 20 or COxe2x80x94C6H4xe2x80x94, wherein the substitution pattern on the phenylene group is an ortho, meta, or para substitution pattern, and one or more of the hydrogens of the phenylene group may be substituted by a hydrocarbyl group or a functional group commonly found in organic molecules; Z is xe2x80x94Oxe2x80x94 or NG, wherein G is H or C1-C12 alkyl; R2 is hydrogen, C1-C8 alkyl, or benzyl; R3, R4, R5, and R6 are each a hydrogen, C1-C8 alkyl, benzyl or phenethyl, or two geminal R moieties, which together with the carbon to which they are attached, form a C5-C10 cycloalkyl; and P is NH or O.
As noted above, in the HALS of formula (II), E, Exe2x80x2 and S are units derived from a piperidin-4-ol or a 4-aminopiperidine moiety and F, Fxe2x80x2 and T are units derived from a multi-functional carbonyl compound and in the HALS of formula (III) F and Fxe2x80x2 are derived from a multi-functional carbonyl compound and M is as defined above. In the HALS of formula (II) it is preferably that the mole percent of the units derived from the multi-functional carbonyl compound is greater than the mole percent of the units derived from a piperidin-4-ol or a 4-aminopiperidine moiety. In the HALS of formula (III) it is preferably that the mole percent of the units derived from the multi-functional carbonyl compound is greater than the mole percent of the diamino or dihydroxy group that contains the 4-aminopiperidine group, i.e., M,. This is advantageous since they are less expensive.
Preferably, in the oligomeric HALS of formula (II), R2 is H, or C1-C4 alkyl; R3, R4, R5, and R6 are each H or C1-C4 alkyl; Ra, Rb, Rc, and Rd, are each a hydrogen, aromatic, or C1-C4 alkyl; n is from about 4 to 11; and s is from about 2 to 5. In a more preferred embodiment, R2 is a hydrogen; R3, R4, R5, and R6 are each methyl; Ra, Rb, Rc, and Rd, are each a hydrogen, Z is O, n is between 4 and 11, and s is 2.
Preferably, in the oligomeric HALS of formula (III), M is N,Nxe2x80x2-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine (BPIP) or N-(2,2,6,6-tetramethylpiperidinol) diethanolamine and n is from about 4 to 11.
Advantageously, the number average molecular weight of the oligomeric HALS compound of formula (II) and (III) is typically from about 400 to 20,000, preferably, from about 1,000 to 15,000, and more preferably from about 2,000 to 9,000.
The present invention also relates to a method of forming oligomeric HALS of formula (II) and formula (III). Oligomeric HALS of formula (II) are prepared by reacting a multi-functional carbonyl compound of general structure
DOxe2x80x94COxe2x80x94CRaRbxe2x80x94(xe2x80x94CRcRdxe2x80x94)nxe2x80x94NHxe2x80x94(Y)mxe2x80x94COxe2x80x94ODxe2x80x83xe2x80x83(IV)
wherein n is an integer from about 1 to 15, preferably 4 to 11, m is either 0 or 1; Ra, Rb, Rc, and Rd, are each a hydrogen or a hydrocarbyl group; Y is COxe2x80x94(CReRf)p, wherein Re and Rf are each a hydrogen or hydrocarbyl group and p is zero or an integer from about 1 to 20 or COxe2x80x94C6H4xe2x80x94, wherein the substitution pattern on the phenylene group may be an ortho, meta, or para substitution pattern, and one or more of the hydrogens of the phenylene group may be substituted by a hydrocarbyl group or a functional group commonly found in organic molecules; and D is a hydrocarbyl group, with a 1-substituted piperidin-4-ol or 4-aminopiperidine of general structure: 
wherein Z is OH or or NHG, wherein G is H or C1-C12 alkyl; R1 is xe2x80x94(CH2)sxe2x80x94OH or xe2x80x94(CH2)sxe2x80x94NH2, wherein s is an integer from about 1 to 10, preferably 2 to 8; R2 represents hydrogen, C1-C8 alkyl, or benzyl; R3, R4, R5, and R6 are each a hydrogen, C1-C8 alkyl, benzyl or phenethyl, or two geminal R moieties, which together with the carbon to which they are attached, form a C5-C10 cycloalkyl.
Oligomeric HALS of formula (III) are prepared by reacting a multi-functional carbonyl compound of general structure (IV) with a diamino or a dihydroxy compound that contains the 4-aminopiperidine group. Preferably, the diamino or dihydroxy compound includes N,Nxe2x80x2-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexanediamine (BPIP) or N-(2,2,6,6-tetramethylpiperidinol)diethanolamine.
The multi-functional carbonyl compounds are prepared by any method available to those of ordinary skill in the art. Preferably, the multi-functional carbonyl compounds are prepared by the method of the invention wherein a carbonyl compound is reacted with a lactam in the presence of a Lewis acid or wherein a carbonyl compound is reacted with a lactam and an alkoxide at a low temperature, i.e., less than 20xc2x0 C. The carbonyl compound, however, must have two reactive carbonyl groups or a single carbonyl group that is activated with two leaving groups (for example, phosgene or a dialkyl carbonate). Preferably, the leaving group is an ester. Preferred carbonyl compound include dialkyl carbonates, dialkyl oxalates, and dialkyl esters.
The reaction can be carried out in the absence of a solvent or in the presence of an organic solvent. When the reaction is carried out in the absence of a solvent, either the multi-functional carbonyl compound or the 1-substituted piperidin-4-ol or 4-aminopiperidine (for compound (II)) or the diamino or dihydroxy compound that contains the 4-aminopiperidine group (for compound (III)) may be present in an excess and employed as the reaction medium. Alternatively, the multi-functional carbonyl compound and the 1-substituted piperidin-4-ol or 4-aminopiperidine or the diamino or a dihydroxy compound that contains the 4-aminopiperidine group can be present in stoichiometric amounts. The reaction can also be conducted in a melt.
Preferably, the reaction is carried out in an organic solvent. Any solvent compatible with the reagents may be used. Preferred solvents for use in the method of the invention include, but are not limited to, hydrocarbon solvents such as a saturated alkanes; benzene; toluene; xylenes; halogenated hydrocarbons; ethers such as ethyl ether; cyclic ethers such as tetrahydrofuran and dioxane; amides such as dimethylformamide; sulfoxides such as dimethylsulfoxide; ketones such as 2-butanone or methyl isobutyl ketone; and the like; or a mixture thereof. The more preferred solvents include toluene, benzene, and xylenes, or a mixture thereof.
The concentration of the multi-functional carbonyl compound in the organic solvent is generally present in an amount of from about 0.025 M to 2.5 M, preferably from about 0.125 M to 0.2 M, and more preferably from about 0.25 M to 1.35 M. The molar ratio of the multi-functional carbonyl compound to the 1-substituted piperidin-4-ol or 4-aminopiperidine, used to prepare the oligomeric HALS of formula (II), or to the diamino or dihydroxy compound that contains the 4-aminopiperidine group, used to prepare the oligomeric HALS of formula (III), is from about 5:1 to 1:5, preferably from about 2:1 to 1:2, and more preferably from about 1.2:1 to 1:1.2.
In a preferred embodiment of the method of making the oligomeric HALS of formula (11), the substituted piperidin-4-ol or 4-aminopiperidine includes N-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-piperidinol. In a preferred embodiment of the method of making the oligomeric HALS of formula (III), the diamino or a dihydroxy compound that contains the 4-aminopiperidine group 4-aminopiperidine includes BPIP or N-(2,2,6,6-tetramethyl piperidinol)diethanolamine or a mixture thereof.
Optionally, but preferably the reaction is conducted in the presence of a catalyst. The catalyst may be a basic catalyst or an acid catalyst. Preferably, the base catalyst is methoxide ion. Preferably the acid catalyst includes a Lewis acid. The preferred Lewis acid includes 1,3-diacetoxy-1,1,3,3-tetrabutyldistannoxane.
The catalyst is typically added in an amount of less than about 30 mole percent by weight based on the weight of the multi-functional carbonyl compound, preferably less than about 20 mole percent by weight based on the weight of the multi-functional carbonyl compound, more preferably less than about 10 mole percent by weight based on the weight of the multi-functional carbonyl compound, and most preferably less than about 5 mole percent by weight based on the weight of the multi-functional carbonyl compound.
The reaction of the multi-functional carbonyl compound and the 1-substituted piperidin-4-ol or 4-aminopiperidine, used to prepare the oligomeric HALS of formula (II), or the diamino or dihydroxy compound that contains the 4-aminopiperidine group, used to prepare the oligomeric HALS of formula (III), is conducted for sufficient time to form a detectable amount of the oligomeric HALS of formula (II) or (III). The reaction time temperature and pressure may readily be determined by one of ordinary skill in the art without undue experimentation. Typically, the reaction time is less than about 20 hours, preferably less than about 15 hours, and more preferably less than about 10 hours. Typically, the reaction temperature is from about room temperature to about 150xc2x0 C., for example, up to the boiling point of the solvent. Preferably, the reaction is carried out at atmospheric pressure. Representative reaction conditions for forming the compound of formula (II) or (III) are provided in the examples.
After the oligomeric HALS of formula (II) or (III) are formed, they are recovered from the reaction mixture by any means available to those of ordinary skill in the art.
In a preferred method, the oligomeric HALS of formula (II) and (III) are formed by reacting a lactam, a carbonyl compound of general structure 
wherein m is either 0 or 1, Q is a good leaving group, such as chloride or OD, wherein D is a hydrocarbyl group, preferably methyl, and B is Q or a hydrocarbyl group and Y is COxe2x80x94(CReRf)p, wherein Re and Rf are each a hydrogen or hydrocarbyl group and p is zero or an integer from about 1 to 20 or COxe2x80x94C6H4xe2x80x94, and the substitution pattern on the phenylene group may be an ortho, meta, or para substitution pattern, in addition one or more of the hydrogens of the phenylene group may be substituted by a hydrocarbyl group or other functional group commonly found in organic molecules, and a 1-substituted piperidin-4-ol or 4-aminopiperidine, in the case of oligomeric HALS of formula (II), or a diamino or a dihydroxy compound, in the case of oligomeric HALS of formula (III), in a single step. The lactam, carbonyl compound, and a 1-substituted piperidin-4-ol or 4-aminopiperidine or a diamino or a dihydroxy compound that contains the 4-aminopiperidine group are combined in a reaction vessel and allowed to react for sufficient time to form a detectable amount of the compound of formula (II) or (III). The ratio of lactam to carbonyl compound is from about 2:1 to 1:4, preferably from about 1:1 to 1:2 and the ratio of lactam to 1-substituted piperidin-4-ol or 4-aminopiperidine or diamino or a dihydroxy compound is from about 2:1 to 1:2, preferably about 1:1.
The single step reaction may be conducted in a solvent or in the absence of a solvent. Preferably, the reaction is conducted in the presence of a solvent. When a solvent is used any solvent that is compatible with the reagents may be used. Representative solvents include, but are not limited to, those solvents described above for the reaction of a 1-substituted piperidin-4-ol or 4-aminopiperidine with a multi-functional carbonyl compound. When a solvent is employed, the concentration of the lactam is typically from about 0.075 M to 10 M, preferably from about 0.375 M to 6 M, and more preferably from about 0.75 M to 4 M.
Optionally, but preferably, the reaction is carried out in the presence of a catalyst. The same catalysts may also be used as were used in the reaction of a 1-substituted piperidin-4-ol or 4-aminopiperidine with a multi-functional carbonyl compound. The catalyst is typically present in an amount of less than about 30 mole percent, preferably less than about mole percent, more preferably less than about 10 mole percent, and most preferably less than 5 mole percent relative to the amount of carbonyl compound.
In general the reaction time is less than about 20 hours, preferably less than about 15 hours, and more preferably less than about 10 hours. Typically, the reaction temperature is from about room temperature to 250xc2x0 C. Preferably, the reaction is carried out at atmospheric pressure. Representative reaction conditions for forming the oligomeric HALS in a single step according to the method of the invention can readily be determined by one of ordinary skill in the art, but guidance is also provided in the examples.
When the oligomeric HALS of formula (II) or (III) is formed it may be recovered from the reaction mixture by any means available to those of ordinary skill in the art.
The HALS of the present invention, i.e., HALS of formula (I) (II), or (III) may be provided as neat compounds or may be provided in the form of a concentrate including from about 15 to 98 percent by weight, and preferably from about 20 to 95 percent by weight, preferably from about 25 to 90 percent by weight, and more preferably from about 40 to 70 percent of at least one of the HALS compounds of formula (I), (II), or (III) and a polymeric resin.
The HALS compounds of the present invention impart superior weatherability and yellowing resistance to polymers. In addition, the HALS compounds of the present invention typically exhibit low volatility. Thus, the present invention also provides polymeric articles stabilized by including an effective amount of the newly discovered HALS compounds to inhibit at least one of photo- or thermal degradation and methods of making the polymeric articles. Any suitable polymer compatible with a HALS composition of the invention may be combined with one or more HALS of the invention to form a polymeric article protected from UV light. The polymeric article includes at least one polymeric material and a sufficient amount of at least one HALS of formula (I), (II), or (III) to inhibit at least one of photo- or thermal degradation. Typically, the polymeric article is stabilized by blending from about 0.01 percent to 10 percent by weight, preferably from about 0.03 percent to 1 percent by weight, and more preferably from about 0.05 percent to 0.5 percent by weight of at least one HALS of formula (I), (II), or (III) with a polymeric material used to form the article. The article may be an extruded article, a molded article, a tape, a film, a fiber, or a coating, for example.
The method of making the polymeric articles includes blending a polymeric material with from about 0.01 percent to 10 percent by weight, preferably from about 0.03 percent to 1 percent by weight, and more preferably from about 0.05 percent to 0.5 percent by weight at least one HALS compounds of the present invention to form a stabilized polymeric composition, and forming an article from the polymeric composition. The polymeric article may be formed by extrusion, sheet extrusion, injection molding, blow molding, injection blow molding, rotational or roto-molding, calendering, thermoforming, compression molding, vacuum molding, pressure molding, reaction injection molding, solvent casting, fiber spinning, and other similar techniques available to those of ordinary skill in the art. The HALS of the invention may be added to the polymeric material by any means known in the art, and one of ordinary skill in the art may readily envision a variety of such ways to combine one or more HALS compounds and one or more polymeric materials to form polymeric articles according to the invention.
A variety of other conventional additives, individually or in combination, may also be added to the polymeric material. Examples of such additives include, but are not limited to one or more of the following classes:
(a) Antioxidants
(i) Alkylated monophenols, such as 2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl-4,6-dimethylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-di-tert-butyl-4-isobutylphenol, 2,6-dicyclopentyl-4-methylphenol, 2-(xcex1-methylcyclohexyl)-4,6-dimethylphenol, 2,6-dioctadecyl-4-methylphenol, 2,4,6-tricyclohexylphenol, 2,6-di-tert-butyl-4-methoxymethylphenol; nonylphenols which are liner or branched in the side chains such as 2,6-di-nonyl-4-methylphenol, 2,4-dimethyl-6-(1-methylundec-1-yl)phenol, 2,4-dimethyl-6-(1-methylheptadec-1-yl)phenol, 2,4-dimethyl-6-(1-methyltridec-1-yl)phenol, CYANOX(copyright) 1790, CYANOX(copyright) 2246, and CYANOX(copyright) 425 Antioxidants, commercially available from CYTEC INDUSTRIES of West Paterson, N.J., IRGANOX(copyright) 1010 Antioxidant and IRGANOX(copyright) 1076 Antioxidant, commercially available from of CIBA SPECIALTIES of Hawthorne, N.Y., and mixtures thereof;
(ii) Alkylthiomethylphenols, such as 2,4-dioctylthiomethyl-6-tert-butylphenol, 2,4-dioctylthiomethyl-6-methylphenol, 2,4-dioctylthiomethyl-6-ethylphenol, 2,6-di-dodecylthiomethyl-4-nonylphenol, and mixtures thereof;
(iii) Hydroquinones and alkylated hydroquinones, such as 2,6-di-tert-butyl-4-methoxyhenol, 2,5-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, 2,6-diphenyl-4-octadecyloxyphenol, 2,6-di-tert-butylhydroquinone, 2,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyanisole, 3,5-di-tert-butyl-4-hydroxyphenyl stearate, and bis(3,5-di-tert-butyl-4-hydroxyphenyl)adipate.
(iv) Tocopherols, such as xcex1-tocopherol (vitamin E), xcex2-tocopherol, xcex3-tocopherol, xcex4-tocopherol, and mixtures thereof;
(v) Hydroxylated thiodiphenyl ethers, such as 2,2xe2x80x2-thiobis(6-tert-butyl-4-methylphenol), 2,2xe2x80x2-thiobis(4-octylphenol), 4,4xe2x80x2-thiobis(6-tert-butyl-3-methylphenol), 4,4xe2x80x2-thiobis(6-tert-butyl-2-methylphenol), 4,4xe2x80x2-thiobis(3,6-di-sec-amylphenol), 4,4xe2x80x2-bis(2,6-dimethyl-4-hydroxyphenyl)disulfide, and mixtures thereof;
(vi) Alkylidenebisphenols, such as 2,2xe2x80x2-methylenebis(6-tert-butyl-4-methylphenol), 2,2xe2x80x2-methylenebis(6-tert-butyl-4-ethylphenol), 2,2xe2x80x2-methylenebis[4-methyl-6-(xcex1-methylcyclohexyl)phenol], 2,2xe2x80x2-methylenebis(4-methyl-6-cyclohexylphenol), 2,2xe2x80x2-methylenebis(6-nonyl-4-methylphenol), 2,2xe2x80x2-methylenebis(4,6-di-tert-butylphenol), 2,2xe2x80x2-ethylidenebis(4,6-di-tert-butylphenol), 2,2xe2x80x2-ethylidenebis(6-tert-butyl-4-isobutylphenol), 2,2xe2x80x2-methylenebis[6-(xcex1-methylbenzyl)-4-nonylphenol], 2,2xe2x80x2-methylenebis[6-(xcex1,xcex1-dimethylbenzyl)-4-nonylphenol], 4,4xe2x80x2-methylenebis(2,6-di-tert-butylphenol), 4,4xe2x80x2-methylenebis(6-tert-butyl-2-methylphenol), 1,1-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, 2,6-bis(3-tert-butyl-5-methyl-2-hydroxylbenzyl)-4-methylphenol, 1,1,3-tris(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, 1,1-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)-3-n-dodecylmercaptobutane, ethylene glycol bis[3,3-bis(3xe2x80x2-tert-butyl-4xe2x80x2-hydroxyphenyl)butyrate], bis(3-tert-butyl-4-hydroxy-5-methylphenyl)dicyclopentadiene, bis[2-(3xe2x80x2-tert-butyl-2xe2x80x2-hydroxy-5xe2x80x2methylbenzyl)-6-tert-butyl-4-methylphenyl]terephthalate, 1,1-bis(3,5-dimethyl-2-hydroxyphenyl)butane, 2,2-bis(3,5-di-tert-butyl-4-hydroxyphenyl)propane, 2,2-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)-4-n-dodecylmercaptobutane, 1,1,5,5-tetra(5-tert-butyl-4-hydroxy-2-methylphenyl)pentane, and mixtures thereof;
(vii) O-, N- and S-benzyl compounds, such as 3,5,3xe2x80x2,5xe2x80x2-tetra-tert-butyl-4,4xe2x80x2-dihydroxydibenzyl ether, octadecyl-4-hydroxy-3,5-dimethylbenzylmercaptoacetate, tridecyl-4-hydroxy-3,5-di-tert-butylbenzylmercaptoacetate, tris(3,5-di-tert-butyl-4-hydroxybenzyl)amine, bis(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)dithioterephthalate, bis(3,5-di-tert-butyl-4-hydroxybenzyl)sulfide, isooctyl-3,5-di-tert-butyl-4-hydroxybenzylmercaptoacetate, and mixtures thereof;
(viii) Hydroxybenzylate malonates, such as dioctadecyl-2,2-bis(3,5-di-tert-butyl-2-hydroxybenzyl)malonate, dioctadecyl-2-(3-tert-butyl-4-hydroxy-5-methylbenzyl)malonate, didodecylmercaptoethyl-2,2-bis(3,5-di-tert-butyl-4-hydroxybenzyl)malonate, bis[4-(1,1,3,3-tetramethylbutyl)phenyl]-2,2-bis(3,5-di-tert-butyl-4-hydroxybenzyl)malonate, and mixtures thereof;
(ix) Aromatic hydroxybenzyl compounds, such as 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, 1,4-bis(3,5-di-tert-butyl-4-hydroxybenzyl)-2,3,5,6-tetramethylbenzene, 2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)phenol, and mixtures thereof;
(x) Triazine compounds, such as 2,4-bis(octylmercapto-6-(3,5-di-tert-butyl-4-hydroxyanilino)-1,3,5-triazine, 2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyanilino)-1,3,5-triazine, 2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,3,5-triazine, 2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,3,5-triazine, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate, 2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenylethyl)-1,3,5-triazine, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)-hexahydro-1,3,5-triazine, 1,3,5-tris(3,5-dicyclohexyl-4-hydroxybenzyl)isocyanurate, and mixtures thereof;
(xi) Benzylphosphonates, such as dimethyl-2,5-di-tert-butyl-4-hydroxybenzylphosphonate, diethyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate, dioctadecyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate, dioctadecyl-5-tert-butyl-4-hydroxy-3-methylbenzylphosphonate, the calcium salt of the monoethyl ester of 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid, and mixtures thereof;
(xii) Acylaminophenols, such as 4-hydroxylauranilide, 4-hydroxystearanilide, and octyl N-(3,5-di-tert-butyl-4-hydroxyphenyl)carbamate, and mixtures thereof;
(xiii) Esters of xcex2-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid; xcex2-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic acid; xcex2-(3,5-dicyclohexyl-4-hydroxyphenyl)propionic acid; 3,5-di-tert-butyl-4-hydroxyphenyl acetic acid with mono- or polyhydric alcohols, such as methanol, ethanol, n-octanol, i-octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N,Nxe2x80x2-bis(hydroxyethyl)oxamide, 3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol, trimethylolpropane, 4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane, and mixtures thereof;
(xiv) Amides of xcex2-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, such as N,Nxe2x80x2-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hexamethylenediamine, N,Nxe2x80x2-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)trimethylenediamine, N,Nxe2x80x2-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hydrazine, and mixtures thereof;
(xv) Ascorbic acid (Vitamin C) or salt or ester thereof;
(xvi) Aminic antioxidants, such as N,Nxe2x80x2-diisopropyl-p-phenylenediamine, N,Nxe2x80x2-di-sec-butyl-p-phenylenediamine, N,Nxe2x80x2-bis(1,4-dimethylpentyl)-p-phenylenediamine, N,Nxe2x80x2-bis(1-ethyl-3-methylpentyl)-p-phenylenediamine, N,Nxe2x80x2-bis(1-methylheptyl)-p-phenylenediamine, N,Nxe2x80x2-dicyclohexyl-p-phenylenediamine, N,Nxe2x80x2-diphenyl-p-phenylenediamine, N,Nxe2x80x2-bis(2-naphthyl)-p-phenylenediamine, N-isopropyl-Nxe2x80x2-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-Nxe2x80x2-phenyl-p-phenylenediamine, N-(1-methylheptyl)-Nxe2x80x2-phenyl-p-phenylenediamine, N-cyclohexyl-Nxe2x80x2-phenyl-p-phenylenediamine, 4-(p-toluenesulfonamoyl)diphenylamine, N,Nxe2x80x2-dimethyl-N,Nxe2x80x2-di-sec-butyl-p-phenylenediamine, diphenylamine, N-allyldiphenylamine, 4-isopropoxydiphenylamine, N-phenyl-1-naphthylamine, N-(4-tert-octylphenyl)-1-naphthylamine, N-phenyl-2-naphthylamine, octylated diphenylamine such as p,pxe2x80x2-di-tert-octyldiphenylamine, 4-n-butylaminophenol, 4-butyrylaminophenol, 4-nonanoylaminophenol, 4-dodecanoylaminophenol, 4-octadecanoylaminophenol, bis(4-methoxyphenyl)amine, 2,6-di-tert-butyl-4-dimethylaminomethylphenol, 2,4xe2x80x2-diaminophenylmethane, 4,4xe2x80x2-diaminodiphenylmethane, N,N,Nxe2x80x2,Nxe2x80x2-tetramethyl-4,4xe2x80x2-diaminodiphenylmethane, 1,2-bis[(2-methylphenyl)amino]ethane, 1,2-bis(phenylamino)propane, (o-tolyl)biguanide, bis[4-(1xe2x80x2,3xe2x80x2-dimethylbutyl)phenyl]amine, tert-octylated N-phenyl-1-naphthylamine, a mixture of mono- and dialkylated tert-butyl/tert-octyldiphenylamines, a mixture of mono- and dialkylated nonyldiphenylamines, a mixture of mono- and dialkylated dodecyldiphenylamines, a mixture of mono- and dialkylated isopropyl/isohexyldiphenylamines, a mixture of mono- and dialkylated tert-butyldiphenylamines, 2,3-dihydro-3,3-dimethyl-4H-1,4-benzothiazine, phenothiazine, a mixture of mono and dialkylated tert-butyl/tert-octyl phenothiazines, a mixture of mono- and dialkylated tert-octylphenothiazines, -allylphenothiazine, N,N,Nxe2x80x2,Nxe2x80x2-tetraphenyl-1,4-diaminobut-2-ene, N,N-bis(2,2,6,6-tetramethylpiperid-4-yl)hexamethylenediamine, bis(2,2,6,6-tetramethylpiperid-4-yl)sebacate, 2,2,6,6-tetramethylpiperidin-4-one, 2,2,6,6-tetramethylpiperidin-4-ol, and mixtures thereof;
(b) Conventional UV-absorbers and light stabilizers
(i) 2-(2xe2x80x2-Hydroxyaryl)benzotriazoles, such as 2-(2xe2x80x2-hydroxy-5xe2x80x2-methylphenyl)-benzotriazole, 2-(3xe2x80x2,5xe2x80x2-di-tert-butyl-2xe2x80x2-hydroxyphenyl)benzotriazole, 2-(5xe2x80x2-tert-butyl-2xe2x80x2-hydroxyphenyl)benzotriazole, 2-(2xe2x80x2-hydroxy-5xe2x80x2-(1,1,3,3-tetramethylbutyl)phenyl)benzotriazole or 2-(2H-benzotriazol-2-yl)-4-tert-octyl-phenol known as CYASORB(copyright) UV-5411 Light Stabilizer, commercially available from CYTEC INDUSTRIES of West Paterson, N.J., 2-(3xe2x80x2,5xe2x80x2-di-tert-butyl-2xe2x80x2-hydroxyphenyl)-5-chlorobenzotriazole, 2-(3xe2x80x2-tert-butyl-2xe2x80x2-hydroxy-5xe2x80x2-methylphenyl)-5-chloro-benzotriazole, 2-(3xe2x80x2-sec-butyl-5xe2x80x2-tert-butyl-2xe2x80x2-hydroxyphenyl)-benzotriazole, 2-(2xe2x80x2-hydroxy-4xe2x80x2-octoxyphenyl)benzotriazole, 2-(3xe2x80x2,5xe2x80x2-di-tert-amyl-2xe2x80x2-hydroxphenyl)benzotriazole, 2-(3xe2x80x2,5xe2x80x2-bis(xcex1,xcex1-dimethylbenzyl)-2xe2x80x2-hydroxyphenyl)-benzotriazole, a mixture of 2-(3xe2x80x2-tert-butyl-2xe2x80x2-hydroxy-5xe2x80x2-(2-octyloxycarbonylethyl)phenyl)-5-chloro-benzotriazole, 2-(3xe2x80x2-tert-butyl-5xe2x80x2-[2-(2-ethylhexyloxy)-carbonylethyl]-2xe2x80x2-hydroxyphenyl)-5-chloro-benzotriazole, 2-(3xe2x80x2-tert-butyl-2xe2x80x2-hydroxy-5xe2x80x2-(2-methoxycarbonylethyl)phenyl)-5-chloro-benzotriazole, 2-(3xe2x80x2-tert-butyl-2xe2x80x2-hydroxy-5xe2x80x2-(2-methoxycarbonylethyl)phenyl)benzotriazole, 2-(3xe2x80x2-tert-butyl-2xe2x80x2-hydroxy-5xe2x80x2-(2-octyloxycarbonylethyl)phenyl)benzotriazole, 2-(3xe2x80x2-tert-butyl-5xe2x80x2-[2-(2-ethylhexyloxy)carbonylethyl]-2xe2x80x2-hydroxyphenyl)benzotriazole, 2-(3xe2x80x2-dodecyl-2xe2x80x2-hydroxy-5xe2x80x2-methylphenyl)benzotriazole and 2-(3xe2x80x2-tert-butyl-2xe2x80x2-hydroxy-5xe2x80x2-(2-isooctyloxycarbonylethyl)phenylbenzotriazole, 2,2-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-benzotriazole-2-yl phenol], the transesterification product of 2-[3xe2x80x2-tert-butyl-5xe2x80x2-(2-methoxycarbonylethyl)-2xe2x80x2-hydroxyphenyl]benzotriazole with polyethylene glycol 300, [Rxe2x80x94CH2CHxe2x80x94COO(CH2)3]2xe2x80x94where R=3xe2x80x2-tert-butyl-4xe2x80x2-hydroxy-5xe2x80x2-2H-benzotriazol-2-yl phenyl, TINUVIN(copyright) 900 Light Stabilizer, commercially available from CIBA SPECIALTIES, and mixtures thereof;
(ii) 2-Hydroxybenzophenones, for example the 4-hydroxy, 4-methoxy, 4-octoxy CYASORB(copyright) UV-531 Light Stabilizer, commercially available from CYTEC INDUSTRIES), 4-decyloxy, 4-dodecyloxy, 4-benzyloxy, 4,2xe2x80x2,4xe2x80x2-trihydroxy and 2xe2x80x2-hydroxy-4,4xe2x80x2-dimethoxy compounds, and mixtures thereof;
(iii) Esters of substituted and unsubstituted benzoic acids or salicylic acid compounds, such as 4-tert-butyl-phenyl salicylate, phenyl salicylate, octylphenyl salicylate, dibenzoyl resorcinol, bis(4-tert-butylbenzoyl) resorcinol, benzoyl resorcinol, 2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate, hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, octadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, and 2-methyl-4,6-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate, and mixtures thereof;
(iv) Acrylates or alkoxycinnamates, such as ethyl xcex1-cyano-xcex2,xcex2-diphenylacrylate, isooctyl xcex1-cyano-xcex2,xcex2-diphenylacrylate, methyl xcex1-carbomethoxycinnamate, methyl xcex1-cyano-xcex2-methyl-p-methoxycinnamate, butyl xcex1-cyano-xcex2-methyl-p-methoxycinnamate, methyl xcex1-carbomethoxy-p-methoxycinnamate, N-(xcex2-carbomethoxy-xcex2-cyanovinyl)-2-methylindoline, and mixtures thereof;
(v) Nickel compounds including nickel (II) complexes of amines and thio-bis-phenols, such as nickel complexes of 2,2xe2x80x2-thio-bis-[4-(1,1,3,3-tetramethylbutyl)phenol], including the 1:1 or 1:2 complex, with or without additional ligands, such as n-butylamine, triethanolamine or N-cyclohexyldiethanolamine, nickel dibutyldithiocarbamate, nickel salts of monoalkyl esters including the methyl or ethyl ester of 4-hydroxy-3,5-di-tert-butylbenzylphosphonic acid, nickel complexes of ketoximes including 2-hydroxy-4-methylphenyl undecyl ketoxime, nickel complexes of 1-phenyl-4-lauroyl-5-hydroxypyrazole, with or without additional ligands, and mixtures thereof;
(vi) Sterically hindered amines, as well as the N compounds thereof (e.g., N-alkyl, N-hydroxy, N-alkoxy and N-acyl), such as bis(2,2,6,6-tetramethylpiperidin-4-yl)sebacate, bis(2,2,6,6-tetramethylpiperidin-4-yl)succinate, bis(1,2,2,6,6-pentamethylpiperidin-4-yl)sebacate, bis(1-octyloxy-2,2,6,6-tetramethylpiperidin-4-yl)sebacate, bis(2,2,6,6-pentamethylpiperidin-4-yl) n-butyl 3,5-di-tert-butyl-4-hydroxybenzylmalonate, the condensate of 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, the condensate of N,Nxe2x80x2-bis(2,2,6,6-tetramethylpiperidin-4-yl)hexamethylenediamine and 4-tert-octylamino-2,6-dichloro-1,3,5-triazine, tris(2,2,6,6-tetramethylpiperidin-4-yl) nitrilotriacetate, tetrakis(2,2,6,6-tetramethylpiperidin-4-yl)-1,2,3,4-butanetetracarboxylate, 1,1xe2x80x2-(1,2-ethanediyl)bis(3,3,5,5-tetramethylpiperazinone), 4-benzoyl-2,2,6,6-tetramethylpiperidine, 4-stearyloxy-2,2,6,6-tetramethylpiperidine, bis(1,2,2,6,6-pentamethylpiperidyl)-2-n-butyl-2-(2-hydroxy-3,5-di-tert-butylbenzyl)malonate, 3-n-octyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decan-2,4-dione, bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl)sebacate, bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl)succinate, the condensate of N,Nxe2x80x2-bis(2,2,6,6-tetramethylpiperidin-4-yl)hexamethylenediamine and 4-morpholino-2,6-dichloro-1,3,5-triazine, the condensate of 2-chloro-4,6-bis(4-n-butylamino-2,2,6,6-tetramethylpiperidyl)-1,3,5-triazine and 1,2-bis(3-aminopropylamino)ethane, the condensate of 2-chloro-4,6-bis(4-n-butylamino-1,2,2,6,6-pentamethylpiperidyl)-1,3,5-triazine and 1,2-bis-(3-aminopropylamino)ethane, 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione, 3-dodecyl-1-(1-ethanoyl-2,2,6,6-tetramethylpiperidin-4-yl)pyrrolidin-2,5-dione, 3-dodecyl-1-(2,2,6,6-tetramethylpiperidin-4-yl)pyrrolidin-2,5-dione, 3-dodecyl-1-(1,2,2,6,6-pentamethylpiperidin-4-yl)pyrrolidine-2,5-dione, a mixture of 4-hexadecyloxy-and 4-stearyloxy-2,2,6,6-tetramethylpiperidine, the condensate of N,Nxe2x80x2-bis(2,2,6,6-tetramethylpiperidin-4-yl)hexamethylenediamine and 4-cyclohexylamino-2,6-dichloro-1,3,5-triazine, the condensate of 1,2-bis(3-aminopropylamino)ethane, 2,4,6-trichloro-1,3,5-triazine and 4-butylamino-2,2,6,6-tetramethylpiperidine (CAS Reg. No. [136504-96-6]), N-(2,2,6,6-tetramethyl piperidine-4-yl)-n-dodecylsuccinimide, N-(1,2,2,6,6-pentamethylpiperidin-4-yl)-n-dodecylsuccinimide, 2-undecyl-7,7,9,9-tetramethyl-1-oxa-3,8-diaza-4-oxospiro-[4.5]decane, oxo-piperanzinyl-triazines or so called PIP-T HALS, e.g., GOODRITE(copyright) 3034, 3150 and 3159 commercially available form BF Goodrich Chemical Co. of Akron, Ohio and similar materials disclosed in U.S. Pat. No. 5,071,981, photobondable HALS such as SANDUVOR(copyright) PR-31 AND PR-32 commercially available from Clariant Corp. of Charlotte N.C., and similar materials disclosed in GB-A-2269819, the reaction product of 7,7,9,9-tetramethyl-2-cycloundecyl-1-oxa-3,8-diaza-4-oxospiro[4.5]decane and epichlorohydrin. Examples of the tetramethylpiperidine derived HALS include CYASORB(copyright) UV-3346 Light Stabilizer, commercially available from CYTEC INDUSTRIES, SANDUVOR(copyright) 3055 HALS, SANDUVOR(copyright) 3056 HALS, and SANDUVOR(copyright) 3058 HALS, commercially available from SANDOZ Corporation of Charlotte, N.C., CHIMASORB(copyright) 944 Stabilizer, TINUVIN(copyright) 622 Stabilizer, and TINUVIN(copyright) 144 Stabilizer, each commercially available from CIBA SPECIALTIES, and mixtures thereof. See also generally U.S. Pat. Nos. 5,106,891, 4,740,542, 4,619,956, 4,426,471, 4,426,472, 4,356,307, 4,344,876, 4,314,933; GB-A-2269819, EP-A-309400, EP-A-309401, EP-A-309402 and EP-A-0434608, each of which is incorporated herein by reference in their entirety;
(vii) Oxamides, oxanilides, benzoxazinones, benzoxazoles, or triazines, such as 2,2xe2x80x2-(1,4-methylene)bis[4H-3,1-benzoxazin-4-one] (CYASORB(copyright) UV-3638 Light Stabilizer, commercially available from CYTEC INDUSTRIES), 4,4xe2x80x2-dioctyloxyoxanilide, 2,2xe2x80x2-diethoxyoxanilide, 2,2xe2x80x2-dioctyloxy-5,5xe2x80x2-di-tert-butoxanilide, 2,2xe2x80x2-didodecyloxy-5,5xe2x80x2-di-tert-butyloxanilide, 2-ethoxy-2xe2x80x2-ethyloxanilide, N,Nxe2x80x2-bis(3-dimethylaminopropyl)oxamide, 2-ethoxy-5-tert-butyl-2xe2x80x2-ethyloxanilide and its mixture with 2-ethoxy-2xe2x80x2-ethyl-5,4xe2x80x2-di-tert-butoxanilide, mixtures of o- and p-methoxy disubstituted oxanilides and mixtures of o- and p-ethoxy disubstitutoctyloxyphenyl-1,3,5-triazine, 2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2,4-bis(2-hydroxy-4-propyloxyphenyl)-6-(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis(4-methylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-dodecyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-tridecyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[2-hydroxy-4-(2-hydroxy-3-butyloxypropyloxy)phenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[2-hydroxy-4-(2-hydroxy-3-octyloxypropyloxy)-phenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[4-dodecyloxy/tridecyloxy-2-hydroxypropoxy)-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[2-hydroxy-4-(2-hydroxy-3-dodecyloxypropoxy)phenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2-hydroxy-4-hexyloxy)phenyl-4,6-diphenyl-1,3,5-triazine, 2-(2-hydroxy-4-methoxyphenyl)-4,6-diphenyl-1,3,5-triazine, 2,4,6-tris[2-hydroxy-4-(3-butoxy-2-hydroxypropoxy)phenyl]-1,3,5-triazine, 2-(2-hydroxyphenyl)-4-(4-methoxyphenyl)-6-phenyl-1,3,5-triazine, and CYAGARD(copyright) UV-1164L Light Stabilizer, commercially available from CYTEC INDUSTRIES, and mixtures thereof;
(c) Metal deactivators, such as N,Nxe2x80x2-diphenyloxamide, N-salicylal-Nxe2x80x2-salicyloyl hydrazine, N,Nxe2x80x2-bis(salicyloyl)hydrazine, N,Nxe2x80x2-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hydrazine, 3-salicyloylamino-1,2,4-triazole, bis(benzylidene)oxalyl dihydrazide, oxanilide, isophthaloyl dihydrazide, sebacoyl bisphenylhydrazide, N,Nxe2x80x2-diacetyladipoyl dihydrazide, N,Nxe2x80x2-bis(salicyloyl)oxalyl dihydrazide, N,Nxe2x80x2-bis(salicyloyl)thiopropionyl dihydrazide, and mixtures thereof;
(d) Phosphites and phosphonites including peroxide decomposers, such as alkyl phosphites, aryl phosphites, and aralkyl phosphites, such as triphenyl phosphite, diphenyl alkyl phosphites, phenyl dialkyl phosphites, tris(nonylphenyl) phosphite, trilauryl phosphite, trioctadecyl phosphite, distearyl pentaerythritol diphosphite ULTRANOX(copyright) 618 Antioxidant, bis-(2,4-di-tert-butylphenyl)pentaerythritoldiphosphite ULTRANOX(copyright) 626 Antioxidant,commercially available from GE Specialty Chemicals of Parkersburg, W. Va., tris(2,4-di-tert-butylphenyl)phosphite, diisodecyl pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, bis(isodecyloxy)pentaerythritol diphosphite, bis(2,4-di-tert-butyl-6-methylphenyl)pentaerythritol diphosphite, bis(2,4,6-tris(tert-butyl)phenyl)pentaerythritol diphosphite, tristearyl sorbitol triphosphite, tetrakis(2,4-di-tert-butylphenyl)-4,4xe2x80x2-biphenylene diphosphonite, 6-isooctyloxy-2,4,8,10-tetra-tert-butyl-12H-dibenzo[d,g]-1,3,2-dioxaphosphocin, 6-fluoro-2,4,8,10-tetra-tert-butyl-12-ethyl-dibenzo[d,g]-1,3,2-dioxaphosphocin, bis(2,4-di-tert-butyl-6-methylphenyl)methylphosphite, bis(2,4-di-tert-butyl-6-methylphenyl)ethylphosphite, and mixtures thereof;
(e) Hydroxylamines, such as N,N-dibenzylhydroxylamine, N,N-diethylhydroxylamine, N,N-dioctylhydroxylamine, N,N-dilaurylhydroxylamine, N,N-ditetradecylhydroxylamine, N,N-dihexadecylhydroxylamine, N,N-dioctadecylhydroxylamine, N-hexadecyl-N-octadecyl-hydroxylamine, -heptadecyl-N-octadecylhydroxylamine, N,N-dialkylhydroxylamine derived from hydrogenated tallow fatty amines, and mixtures thereof;
(f) Nitrones, such as N-benzyl-alpha-phenyl nitrone, N-ethyl-alpha-methyl nitrone, N-octyl-alpha-heptyl nitrone, N-lauryl-alpha-undecyl nitrone, N-tetradecyl-alpha-tridecyl nitrone, N-hexadecyl-alpha-pentadecyl nitrone, N-octadecyl-alpha-heptadecyl nitrone, N-hexadecyl-alpha-heptadecyl nitrone, N-octadecyl-alpha-pentadecyl nitrone, N-heptadecyl-alpha-heptadecyl nitrone, N-octadecyl-alpha-hexadecyl nitrone, nitrones derived from N,N-dialkylhydroxylamines prepared from hydrogenated tallow fatty amines, and mixtures thereof;
(g) Thiosynergists, such as dilauryl thiodipropionate and distearyl thiodipropionate, and mixtures thereof;
(h) Peroxide scavengers such as esters of xcex2-thiodipropionic acid, for example the lauryl, stearyl, myristyl or tridecyl esters, mercaptobenzimidazole or the zinc salt of 2-mercaptobenzimidazole, zinc dibutyldithiocarbamate, dioctadecyl disulfide, pentaerythritol tetrakis(xcex2-dodecylmercapto)propionate, and mixtures thereof;
(i) Polyamide stabilizers, such as copper salts in combination with iodides and/or phosphorus compounds and salts of divalent manganese, and mixtures thereof;
(j) Basic co-stabilizers, such as melamine, polyvinylpyrrolidone, dicyandiamide, triallyl cyanurate, urea compounds, hydrazine compounds, amines, polyamides, polyurethanes, alkali metal salts and alkaline earth metal salts of higher fatty acids, for example calcium stearate, zinc stearate, magnesium behenate, magnesium stearate, sodium ricinoleate and potassium palmitate, antimony pyrocatecholate, tin pyrocatecholate, and mixtures thereof;
(k) Nucleating agents including inorganic substances, such as talc and metal oxides (e.g., titanium oxide or magnesium oxide), and phosphates, carbonates and sulfates of, preferably, alkaline earth metals; organic compounds, such as mono- or polycarboxylic acids and salts thereof, for example 4-tert-butylbenzoic acid, adipic acid, diphenylacetic acid, sodium succinate and sodium benzoate; polymeric compounds such as ionic copolymers (xe2x80x9cionomersxe2x80x9d), and mixtures thereof;
(l) Fillers and reinforcing agents, such as calcium carbonate, silicates, glass fibers, asbestos, talc, kaolin, mica, barium sulfate, metal oxides and hydroxides, carbon black, graphite, wood flour and flours or fibers from other natural products, and synthetic fibers, and mixtures thereof;
(m) Benzofuranones and indolinones, such as those disclosed in U.S. Pat. Nos. 4,325,863, 4,338,244, 5,175,312, 5,216,052, and 5,252,643, and DE-A-4316611, DE-A-4316622, DE-A-4316876, EP-A-0589839 and EP-A-0591102; 3-[4-(2-acetoxy-ethoxy)phenyl]-5,7-di-tert-butyl-benzofuran-2-one, 5,7-di-tert-butyl-3-[4-(2-stearoyloxyethoxy)-phenyl]benzofuran-2-one, 3,3xe2x80x2-bis[5,7-di-tert-butyl-3-(4-[2-hydroxyethoxy]phenyl)benzofuran-2-one], 5,7-di-tert-butyl-3-(4-ethoxyphenyl)benzofuran-2-one, 3-(4-acetoxy-3,5-dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2-one, 3-(3,5-dimethyl-4-pivaloyloxyphenyl)-5,7-di-tert-butyl-benzofuran-2-one, and mixtures thereof;
(n) Sulfur containing antioxidants, such as organic sulfides and disulfides and include distearyl thiodipropionate CYANOX(copyright) STDP Antioxidant, commercially available from CYTEC INDUSTRIES, pentaerythritol tetrakis(beta-laurylthiopropionate) SEENOX(copyright) 412 S Antioxidant, commercially available from Witco Chemical Corporation of Brooklyn, N.Y., and mixtures thereof. A person skilled in the art is well aware, for example, that any one or more of these additives may be combined, such as in CYANOX(copyright) 2777 Antioxidant, commercially available from CYTEC INDUSTRIES, which combines a phenolic antioxidant and a phosphite antioxidant. The composition may contain quenchers such as CYASORB(copyright) UV-1084 Light Stabilizer, CYASORB(copyright) UV-531 Light Stabilizer, each commercially available from CYTEC INDUSTRIES.
(o) Other additives, such as acid scavengers, antistatic agents, blowing agents, catalysts, clarifying agents, emulsifiers, fillers, flameproofing agents, fluorescent whitening agents, infrared absorbers, levelling assistants, lubricants, metal deactivators, mold release agents, nucleating agents, optical brighteners, pigments, plasticizers, rheological additives, and mixtures thereof.
The total amount of additives may be present in an amount up to about 10 percent, preferably from about 0.1 percent to about 5 percent by weight, and more preferably from about 0.2 percent to 3 percent by weight, based on the weight of the polymer.
The light-stabilized polymeric article may be formed from a polymeric material by incorporating the presently claimed compounds into polymeric materials, either chemically or physically. Non-limiting examples of polymeric materials that may be so stabilized are polyolefins; polyesters; polyethers; polyketones; polyamides; natural and synthetic rubbers; polyurethanes; polystyrenes; high-impact polystyrenes; polyacrylates; polymethacrylates; polyacetals; polyacrylonitriles; polybutadienes; polystyrenes; ABS; SAN (styrene acrylonitrile); ASA (acrylate styrene acrylonitrile); cellulosic acetate butyrate; cellulosic polymers; polyimides; polyamideimides; polyetherimides; polyphenylsulfides; PPO; polysulfones; polyethersulfones; polyvinylchlorides; polycarbonates; polyketones; aliphatic polyketones; thermoplastic TPO""s; aminoresin crosslinked polyacrylates and polyesters; polyisocyanate crosslinked polyesters and polyacrylates; phenol/formaldehyde, urea/formaldehyde, and melamine/formaldehyde resins; drying and non-drying alkyd resins; alkyd resins; polyester resins; acrylate resins cross-linked with melamine resins, urea resins, isocyanates, isocyanurates, carbamates, and epoxy resins; cross-linked epoxy resins derived from aliphatic, cycloaliphatic, heterocyclic and aromatic glycidyl compounds which are cross-linked with anhydrides or amines; polysiloxanes; Michael addition polymers of amines or blocked amines with activated unsaturated and methylene compounds, ketimines with activated unsaturated and methylene compounds, polyketimines in combination with unsaturated acrylic polyacetoacetate resins, and polyketimines in combination with unsaturated acrylic resins; radiation curable compositions; epoxymelamine resins; organic dyes; cosmetic products; cellulose-based paper formulations; photographic film paper; ink; and blends thereof.
The degradable polymer may be any polymer requiring stabilization, and includes homopolymers and copolymers of various monomers. It may be an addition polymer, a condensation polymer, a graft polymer, a thermosetting polymer, a photopolymer, a polymer blend or a thermoplastic polymer. It may be in the form of a fiber, a polymer film such as polypropylene films, a thin film such a solvent based coating, a water-based coating, a stoving lacquer, a powder coating, a gel coat, and the like, or it may be in the form of a molded article. Examples of degradable polymers which can be stabilized include, but are not limited to:
1. Homo- and copolymers of monoolefins and diolefins including, but not limited to, ethylene, propylene, isobutylene, butene, methylpentene, hexene, heptene, octene, isoprene, butadiene, hexadiene, dicyclopentadiene, ethylidene, and cycloolefins such as cyclopentene and norbornene; for example, polyethylenes (which optionally can be cross-linked) such as high density polyethylene (HDPE), high density and high molecular weight polyethylene (HDPE-HMW), high density and ultrahigh molecular weight polyethylene (HDPE-UHMW), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), branched low density polyethylene (BLDPE) or polypropylene (PP) or polymers of ethylene propylene diene monomer (EPDM); and blends thereof.
2. Copolymers of one or more monoolefins and/or diolefins with carbon monoxide and/or with other vinyl monomers, including acrylic and methacrylic acid, acrylates and methacrylates, acrylamides, acrylonitriles, styrenes, vinyl acetate (such as ethylene/vinyl acetate copolymers (EVA)), vinyl halides, vinylidene halides, maleic anhydride, and allyl monomers such as allyl alcohol, allyl amine, allyl glycidyl ether and compounds thereof; and blends thereof.
3. Hydrocarbon resins (such as C5-C9) including hydrogenated modifications thereof, and mixtures of polyalkylenes and starch; and blends thereof.
4. Homo- and copolymers of styrenes such as styrene, p-methylstyrene and xcex1-methylstyrene such as polystyrene, polyalphamethylstyrene, high impact polystyrene (HIPS); and blends thereof.
5. Copolymers of one or more styrenes with other vinyl monomers such as olefins and diolefins (e.g., ethylene, isoprene and/or butadiene), acrylic and methacrylic acid, acrylates and methacrylates, acrylamides, acrylonitriles, vinyl acetate (such as ethylene/vinyl acetate copolymers), vinyl halides, vinylidene halides, maleic anhydride and allyl compounds such as allyl alcohol, allyl amine, allyl glycidyl ether; and blends thereof.
6. Graft copolymers of styrenes on polybutadienes, polybutadiene/styrene copolymers and polybutadiene/acrylonitrile copolymers; styrene (or a-methylstyrene) and acrylonitrile (or methacrylonitrile) on polybutadiene; styrene and maleic anhydride on polybutadiene; styrene, acrylonitrile and maleic anhydride or maleimide on polybutadiene; acrylonitrile/styrene/acrylonitrile polymers (ASA) styrene and acrylonitrile on ethylene/propylene/diene copolymers; styrene and acrylonitrile on polyalkyl acrylates or methacrylates; and styrene and acrylonitrile on acrylate/butadiene (ABS) copolymers; and blends thereof.
7. Halogen-containing polymers such as poly vinyl chloride (PVC), chlorinated polyethylene (CPE), or polychloroprene; chlorinated rubbers; chlorinated and brominated isobutylene/isoprene copolymers; chlorinated or sulfochlorinated polyethylene; copolymers of ethylene and chlorinated ethylene; epichlorohydrin polymers and copolymers; and polymers and copolymers of halogen-containing vinyl compounds such as vinyl chloride, vinylidene chloride, vinyl fluoride and/or vinylidene fluoride, other vinyl monomers or other polyvinyl halides; and blends thereof.
8. Homo- and copolymers derived from xcex1,xcex2-unsaturated acids and compounds thereof such as acrylic acid, methacrylic acid, acrylates, methacrylates, acrylamides and acrylonitriles; and blends thereof.
9. Copolymers of the monomers mentioned in (5) above with other unsaturated monomers such as olefins and diolefins (e.g., butadiene), styrenes, vinyl halides, maleic anhydride and allyl monomer such as allyl alcohol, allyl amine, allyl glycidyl ether; and blends thereof.
10. Homo- and copolymers derived from unsaturated alcohols and amines or the acyl compounds or acetals thereof, such as vinyl alcohol (including polyvinyl alcohol cross-linked polyvinyl alcohol), vinyl acetate, vinyl stearate, vinyl benzoate, vinyl maleate, vinyl butyral, allyl alcohol, allyl amine, allyl glycidyl ether, allyl phthalate and allyl melamine; as well as copolymers of such monomers with other ethylenic unsaturated monomers mentioned above; and blends thereof.
11. Homo- and copolymers of cyclic ethers such as alkylene glycols and alkylene oxides, as well as copolymers with bisglycidyl ethers; and blends thereof.
12. Polyacetals such as polyoxymethylene (POM) and those polyoxymethylenes which contain ethylene oxide as a comonomer; and polyoxymethylenes modified with thermoplastic polyurethanes, acrylates and/or MBS; and blends thereof.
13. Polyphenylene oxides (PPO) and sulfides; and blends thereof.
14. Polyurethanes (PUR) derived from hydroxy-functional components such as polyhydric alcohols, polyethers, polyesters, polyacrylics and/or polybutadienes on the one hand, and aliphatic and/or aromatic isocyanates on the other, as well as precursors thereof including isocyanate cross-linked polymers; and blends thereof.
15. Polyamides (PA) and copolyamides derived from diamines, dicarboxylic acids and/or aminocarboxylic acids or the corresponding lactams, such as NYLON(copyright) plastics, e.g., polyamide 4, polyamide 6, polyamide 6/6, polyamide 6/10, polyamide 6/9, polyamide 6/12, polyamide 4/6, polyamide 12/12, polyamide 11 and polyamide 12; aromatic polyamides starting from m-xylene diamine and adipic acid; polyamides prepared from hexamethylene diamine and isophthalic and/or terephthalic acid and with or without an elastomer as a modifier, for example, poly-2,4,4-trimethylhexamethylene terephthalamide or poly-m-phenylene isophthalamide; block copolymers of the aforementioned polyamides with polyolefins, olefin copolymer, ionomers, chemically bonded or grafted elastomer, or polyethers such as polyepoxides, polyethylene glycol, polypropylene glycol or polytetramethylene glycol; and polyamides condensed during processing (RIM polyamide systems); and blends thereof.
16. Polyureas, polyimides, polyamide-imides, polyetherimides, polyesterimides, polyhydantoins and polybenzimidazoles; and blends thereof.
17. Polyesters derived from dicarboxylic acids, diols and/or hydroxycarboxylic acids or the corresponding lactones, such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene terephthalate, glycol modified (PETG), polyethylene terephthalate modified with 1,4-cyclohexanedimethanol (PCTG),poly-1,4-dimethylcyclohexane terepthalate and polyhydroxybenzoates, as well as block copolyether esters derived from hydroxyl-terminated ethers; and also polyesters modified with polycarbonate or MBS; PEN, PTT; and blends thereof.
18. Polycarbonates (PC) and polyester carbonates such as resins are polycarbonates based on dihydric phenols such as 2,2-bis-(4-hydroxyphenyl)propane (bisphenol A); 2,4-bis (4-hydroxyphenyl)-2-methylbutane; 1,1-bis-(4-hydroxyphenyl)-cyclohexane; 2,2-bis-(3-chloro-4-hydroxyphenyl)propane; 4,4xe2x80x2-sulfonyldiphenol; and 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane; and blends thereof. Also preferred are polycarbonate copolymers incorporating two or more phenols, branched polycarbonates wherein a polyfunctional aromatic compound is reacted with a dihydric phenol(s) and carbonate precursor, and polymer blends of which polycarbonate comprises a significant portion of the blend (i.e., more than 20%, preferably more than 50%). Preferred resins for both layers are polycarbonates based on bisphenol A.
U.S. Pat. No. 5,288,788 also describes polycarbonates and polyester carbonates, especially aromatic polycarbonates, for example those based on 2,2-bis(4-hydroxyphenyl)propane or 1,1-bis(4-hydroxyphenyl)cyclohexane. Mixtures (polyblends) of such polymers with one another or with other polymers, for example with polyolefins, polyacrylates, polydienes or other elastomers in the form of impact strength modifiers can also be stabilized with the HALS compounds of the invention.
Among those compounds, preference is given to the polycarbonates, polyesters, polyamides, polyacetals, polyphenylene oxides and polyphenylene sulfides, but especially to the polycarbonates. Those compounds are to be understood as being especially those polymers the constitutional repeating unit of which corresponds to the formula: 
wherein A is a divalent phenolic radical. Suitable examples of A are given in U.S. Pat. No. 4,960,863 and DE-A-3 922,496 whose contents are incorporated herein by reference thereto. xe2x80x9cAxe2x80x9d can be derived, for example, from hydroquinone, resorcinol, dihydroxybiphenylene or bisphenols in the broadest sense of the term, such as bis(hydroxyphenyl)alkanes, cycloalkanes, sulfides, ethers, ketones, sulfones, sulfoxides, xcex1,xcex1xe2x80x2-bis(hydroxyphenyl)-diisopropylbenzenes, for example the compounds 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)-propane, 2,2-bis(3,5-dichloro-4-hydroxyphenyl)propane, 1,1-bis(4-hydroxypehnyl)cyclohexane, or from the compounds of the formula: 
19. Polysulfones, polyether sulfones and polyether ketones.
20. Cross-linked polymers derived from aldehydes condensation resins such as phenol/formaldehyde resins, urea/formaldehyde resins and melamine/formaldehyde resins; and blends thereof.
21. Drying and non-drying alkyd resins; and blends thereof.
22. Unsaturated polyester resins derived from copolyesters of saturated and unsaturated dicarboxylic acids with polyhydric alcohols and vinyl compounds as crosslinking agents, and also halogen-containing modifications thereof; and blends thereof.
23. Cross-linkable acrylic resins derived from substituted acrylates such as epoxy acrylates, hydroxy acrylates, isocyanato acrylates, urethane acrylates or polyester acrylates; and blends thereof.
24. Alkyd resins, polyester resins and acrylate resins cross-linked with melamine resins, urea resins, isocyanates, isocyanurates, carbamates or epoxy resins; and blends thereof.
25. Cross-linked epoxy resins derived from aliphatic, cycloaliphatic, heterocyclic and/or aromatic glycidyl compounds such as bisphenol A and bisphenol F, which are cross-linked with customary hardeners such as anhydrides or amines; and blends thereof.
26. Natural polymers such as cellulose, rubber, gelatin and chemically modified homologous compounds thereof, including cellulose acetates, cellulose propionates and cellulose butyrates, nitrocellulose, or the cellulose ethers such as methyl cellulose, as well as rosins and their compounds; and blends thereof.
27. Polysiloxanes; and blends thereof.
28. Michael addition polymers of amines or blocked amines (e.g., ketimines) with activated unsaturated and/or methylene compounds such as acrylates and methacrylates, maleates and acetoacetates; and blends thereof.
29. Mixtures or blends of any of the above, such as PP/EPDM, polyamide/EPDM or ABS, PVC/EVA, PVC/ABS, PVC/MBS, PC/ABS, PBTP/ABS, PC/ASA, PC/PBT, PVC/CPE, PVC/acrylate, POM/thermoplastic PUR, PC/thermoplastic polyurethane, POM/acrylate, POM/MBS, PPO/HIPS, PPO/PA6.6 and copolymers, PA/HDPE, PP/HDPE, PP/LDPE, LDPE/HDPE, LDPE/EVA, LDPE/EAA, PA/PP, PA/PPO, PBT/PC/ABS, PBT/PET/PC and the like.
30. Naturally occurring and synthetic organic materials which may be mixtures of compounds, including mineral oils, animal and vegetable fats, oils and waxes, or oils, fats or waxes based on synthetic esters (e.g., phthalates, adipates, phosphates or trimellitates) and also mixtures of synthetic esters with mineral oils in any ratio.
31. Aqueous emulsions of natural or synthetic rubber such as natural latex or latexes of carboxylated styrene/butadiene copolymers; and blends thereof.
32. Polyketimines in combination with unsaturated acrylic polyacetoacetate resins or with unsaturated acrylic resins including urethane acrylates, polyether acrylates, vinyl or acryl copolymers with pendant unsaturated groups and acrylated melamines; and blends thereof.
33. Radiation curable compositions containing ethylenically unsaturated monomers or oligomers and a polyunsaturated aliphatic oligomer; and blends thereof.
34. Epoxymelamine resins such as light-stable epoxy resins cross-linked by an epoxy functional coetherified high solids melamine resin. The aminoresin-cross-linked polymer may be an aminoresin-cross-linked thermoset acrylic or an aminoresin-cross-linked thermoset polyester. The suitable aminoresins include alkylated and unalkylated melamine-formaldehyde resins, guanamine-formaldehyde resins, urea-formaldehyde resins, glycouril formaldehyde resins, and the like; and blends thereof.
35. Organic dyes such as azo dyes (diazo, triazo, and polyazo), anthraquinones, benzodifuranones, polycyclic aromatic carbonyl dyes, indigoid dyes, polymethines, styryl dyes, di- and triaryl carbonium dyes, phthalocyanines, quinophthalones, sulfur dyes, nitro and nitroso dyes, stilbene dyes, formazan dyes, quinacridones, carbazoles, and perylene tetracarboxylic diimides; and blends thereof.
36. Cosmetic products, such as skin lotions, collagen creams, sunscreen, facial make-up, etc., comprising synthetic materials such as antioxidants, preservatives, lipids, solvents surfactants, colorants, antiperspirants, skin conditioners, moisturizers etc.; as well as natural products such as collagen, proteins, mink oil, olive oil, coconut oil, carnauba wax, beeswax, lanolin, cocoa butter, xanthan gum, aloe, etc; and blends thereof.
37. Cellulose-based paper formulations for use, e.g., in newsprint, cardboard, posters, packaging, labels, stationery, book and magazine paper, bond typing paper, multi-purpose and office paper, computer paper, xerographic paper, laser and ink-jet printer paper, offset paper, currency paper, etc., and combinations thereof.
38. Photographic film paper.
39. Ink.
The term xe2x80x9ccopolymer,xe2x80x9d as used herein, is a polymer of two or more different monomers. Preferably, the light-stabilized polymeric material is formed from a polyolefin homopolymer or copolymer, and more preferably a homopolymer or copolymer of polyethylene or polypropylene.
The novel HALS of the present invention can also be employed in multilayer systems. In such systems, a polymer composition having from about 0.1 to 20 percent by weight and preferably having a relatively high content of the novel HALS of the invention, for example, from about 5 to 15 percent by weight, is applied in a thin film (typically between about 5 to 500 xcexcm and preferably from about 10 to 100 xcexcm thick) to a shaped article made from a polymer containing little or no ultraviolet stabilizers. Such composition may be applied at the same time as the shaping of the base structure, for example by coextrusion. Alternatively, application can also be made to the ready-formed base structure, for example by lamination with a film or by coating with a solution. The outer layer or layers of the finished article have the function of a UV filter, which protects the interior of the article from UV light. The outer layer preferably contains about 0.1 to 20 percent, preferably about 1 to 15 percent and more preferably about 2 to 10 percent by weight of the outer layer composition, of at least one of the HALS of the present invention.
British Patent Appn. No. 2,290,745 describes a number of methods that have been developed to concentrate UV absorbers near or at the surface of polymeric materials. These include surface impregnation (see U.S. Pat. Nos. 3,309,220, 3,043,709, 4,481,664 and 4,937,026) and coating a plastic article with solutions containing thermoplastic resins and UV absorbers (see U.S. Pat. Nos. 4,668,588 and 4,353,965). Both techniques, however, suffer from drawbacks such as requiring additional processing steps (i.e., applying, drying or curing), and encounter difficulties associated with the handling of large processed articles. An additional drawback, particularly relevant to polycarbonate sheet production, is the detrimental effect such post addition treatment would have on the surface of the polymeric substrate.
As described in the U.S. Pat. No. 5,445,872, application of surface layers via coextrusion takes place in a known manner with known coextrusion equipment as taught in U.S. Pat. Nos. 3,487,505 and 3,557,265, which is a preferred way to incorporate HALS compounds onto the surface of a polymeric article according to the present invention. Coextrusion is a well recognized method of producing laminated thermoplastic materials by simultaneously extruding various numbers of layers which form a single composite material. U.S. Pat. No. 4,540,623 describes coextruded materials of at least forty layers. Other methods known to those of ordinary skill in the art produce as few as two or three different layers.
In one embodiment, the invention relates to thermoplastic articles coated with a thermoplastic layer about 0.1 to 10 mil (0.00254 mm to 0.254 mm) thick, preferable about 0.1 to 5 mil (0.00254 mm to 0.127 mm) thick, in which the layer contains between about 0.1% to 20% by weight of one or more of the HALS of the invention. Preferred concentrations are from about 2% to 15% by weight; most preferred are concentrations from about 5% to 10% by weight.
The HALS of the instant invention may be incorporated into the thermoplastics of the surface layer by standard methods, such as dry mixing the additives with a granular resin prior to extruding. The HALS layer may be applied to one or more sides of a thermoplastic article according to the present invention.
Laminated thermoplastic articles corresponding to the present invention which contain additional layers such as a water resistant layer, as found in U.S. Pat. No. 4,992,322, are also within the scope of the present invention.
The core layer and the coating layer may be of the same thermoplastic resin or different. Examples of thermoplastic resins include thermoplastic polyesters, polyester carbonates, polyphenylene oxide, polyvinyl chloride, polypropylene, polypropylene, polyethylene, polyacrylates, polymethacrylates and copolymers and blends such as styrene and acrylonitrile on polybutadiene and styrene with maleic anhydride; and blends thereof.
The polymers stabilized in this way are notable for high weathering resistance, especially for high resistance to UV light. This enables them to substantially retain their mechanical properties and their color and gloss for a long time even when used in harsh environments.
In another embodiment of the present invention, novel mixtures comprising at least one HALS of the invention can be used as stabilizers for coatings, for example for paints. Of particular interest are coatings and paints for the automobile industry. xe2x80x9cCoatingxe2x80x9d means a free flowing composition that can be applied to the surface of an article in a thin film that then hardens to form a substantially solid surface on the article. Typically, the coating provides an interface between the article and the environment.
Such novel coating compositions comprise from about 0.01 to 20 percent, preferably from about 0.01 to 10 percent and more preferably from about 0.02 to 5 percent by weight of one or more of the HALS of the present invention.
The coating may be applied to the surface of the article in one or more than one layer to provide a multilayered system. In multilayer systems, the concentration of the novel HALS compounds in the outer layer can be relatively high, for example from about 0.01 to 20 percent, preferably from about 0.01 to 10 percent, and more preferably from about 0.02 to 5 percent by weight.
The use of the novel stabilizer in coatings is accompanied by the additional advantage that it inhibits or prevents delamination, i.e., the flaking-off of the coating from the substrate. This advantage is particularly important in the case of metallic substrates, including multilayer systems on metallic substrates, which have such flaking tendencies.
The coatings typically include a binder that suspends pigments and other additives in the coating and allows attachment of the coating to the substrate.
The binder can in principle be any binder which is customary in industry, for example those described in Ullmann""s Encyclopedia of Industrial Chemistry, 5th Edition, Vol. A18, pp. 368-426, VCH, Weinheim, 1991, which is incorporated herein by reference. In general, it is a film-forming binder based on a thermoplastic or thermosetting resin, predominantly on a thermosetting resin. Examples thereof are alkyd, acrylic, polyester, phenolic, melamine, epoxy, and polyurethane resins, and mixtures thereof.
Such binders can be a cold-curable or hot-curable binder. Further, in some systems it may be advantageous to add a curing catalyst to such systems. Suitable catalysts which accelerate curing of the binder are described, for example, in Ullmann""s Encyclopedia of Industrial Chemistry, Vol. A18, p. 469, VCH Verlagsgesellschaft, Weinheim, 1991, which is incorporated herein by reference.
Preferred binders include those which comprise a functional acrylate resin and a crosslinking agent.
A wide variety of binders may be employed in such coating systems. Examples of suitable coating compositions containing specific binders, include but are not limited to:
1. paints based on cold- or hot-cross-linkable alkyd, acrylate, polyester, epoxy or melamine resins, or mixtures of such resins, if desired with addition of a curing catalyst;
2. two-component polyurethane paints based on hydroxyl-containing acrylate, polyester or polyether resins and aliphatic or aromatic isocyanates, isocyanurates or polyisocyanates; or mixtures thereof;
3. one-component polyurethane paints based on blocked isocyanates, isocyanurates or polyisocyanates which are deblocked during baking;or mixtures thereof;
4. two-component paints based on (poly)ketimines and aliphatic or aromatic isocyanates, isocyanurates or polyisocyanates; or mixtures thereof;
5. two-component paints based on (poly)ketimines and an unsaturated acrylate resin or a polyacetoacetate resin or a methacrylamidoglycolate methyl ester; or mixtures thereof;
6. two-component paints based on carboxyl- or amino-containing polyacrylates and polyepoxides; or mixtures thereof;
7. two-component paints based on acrylate resins containing anhydride groups and on a polyhydroxy or polyamino component; or mixtures thereof;
8. two-component paints based on (poly)oxazolines and acrylate resins containing anhydride groups, or unsaturated acrylate resins, or aliphatic or aromatic isocyanates, isocyanurates or polyisocyanates; or mixtures thereof;
9. two-component paints based on unsaturated polyacrylates and polymalonates; or mixtures thereof;
10. thermoplastic polyacrylate paints based on thermoplastic acrylate resins or externally crosslinking acrylate resins in combination with etherified melamine resins; or mixtures thereof;
11. paint systems based on siloxane-modified or fluorine-modified acrylate resins or mixtures thereof;
In addition to the binder and novel HALS of the present invention, the coating composition according to the invention may further comprise one or more additional additives, such as an antioxidant or additional ultraviolet light absorber or stabilizer. Additional additives include, but are not limited to, those specifically listed above. The additional additive is employed in coating compositions in an amount of from about 0.01 to 5 percent, preferably from about 0.02 to 2 percent by weight.
In addition, well known to those of ordinary skill in the art to be suitable for coating compositions the coating composition can also comprise further components including, but not limited to, solvents, pigments, dyes, plasticizers, stabilizers, thixotropic agents, drying catalysts and/or leveling agents, or combinations thereof. Examples of possible components are those described in Ullmann""s Encyclopedia of Industrial Chemistry, 5th Edition, Vol. A18, pp. 429-471, VCH, Weinheim 1991, which is incorporated herein by reference.
Exemplary drying catalysts or curing catalysts are, for example, organometallic compounds, amines, amino-containing resins and/or phosphines. Examples of organometallic compounds are metal carboxylates, especially those of the metals Pb, Mn, Co, Zn, Zr or Cu, or metal chelates, especially those of the metal Al, Ti or Zr, or organometallic compounds such as organotin compounds, for example, and mixtures thereof.
Examples of metal carboxylates are the stearates of Pb, Mn or Zn, the octoates of Co, Zn or Cu, the naphthenates of Mn and Co or the corresponding linoleates, resinates or tallates, and mixtures thereof.
Examples of metal chelates are the aluminum, titanium, or zirconium chelates of acetylacetone, ethyl acetylacetate, salicylaldehyde, salicylaldoxime, o-hydroxyacetophenone, or ethyl trifluoroacetylacetate, and the alkoxides of these metals, and mixtures thereof.
Examples of organotin compounds are dibutyltin oxide, dibutyltin dilaurate or dibutyltin dioctoate, and mixtures thereof.
Examples of amines are, in particular, tertiary amines, for example tributylamine, triethanolamine, N-methyldiethanolamine, N-dimethylethanolamine, N-ethylmorpholine, N-methylmorpholine or diazabicyclooctane (triethylenediamine) and salts thereof, and mixtures thereof. Further examples are quaternary ammonium salts, for example trimethylbenzylammonium chloride. Amino-containing resins are simultaneously a binder and a curing catalyst. Examples thereof are amino-containing acrylate copolymers.
The curing catalyst used can also be a phosphine, for example triphenylphosphine.
The novel coating compositions can also be radiation-curable coating compositions. In this case, the binder includes monomeric or oligomeric compounds containing ethylenically unsaturated bonds, which after application are cured by actinic radiation, i.e., converted into a crosslinked, high molecular weight form. Where the system is UV-curable, it generally contains a photoinitiator as well. Corresponding systems are described in the above-mentioned publication Ullmann""s Encyclopedia of Industrial Chemistry, 5th Edition, Vol. A18, pages 451-453, which is incorporated herein by reference. In radiation-curable coating compositions, the novel stabilizers can also be employed with or without additional UV light stabilizers, including sterically hindered amines.
The coating compositions according to the invention can be applied to any desired substrates, for example to metal, wood, plastic, or ceramic materials. They are preferably used as topcoats in the finishing of automobiles. If the topcoat comprises two layers, of which the lower layer is pigmented and the upper layer is not pigmented, the novel coating composition can be used for either the upper or the lower layer or for both layers, but preferably for the upper layer.
The novel coating compositions can be applied to the substrates by any conventional methods available to those or ordinary skill in the art, for example by brushing, spraying, pouring, dipping, or electrophoresis; see also Ullmann""s Encyclopedia of Industrial Chemistry, 5th Edition, Vol. A18, pp. 491-500, which is incorporated herein by reference.
Depending on the binder system, the coatings can be cured at room temperature or may require heating. The coatings are preferably cured at a temperature of from about 50xc2x0 C. to 150xc2x0 C., and in the case of powder coatings, even at higher temperatures.
The coatings obtained in accordance with the invention generally have excellent resistance to the damaging effects of light, oxygen, and heat. In particular, the presently claimed coatings provide good light stability and weathering resistance.
The invention therefore encompasses coatings, in particular a paint, which has been stabilized against the damaging effects of light, oxygen, and/or heat by a content of at least one of the HALS of the present invention incorporated into or onto an article. The paint may be a pigmented mono-coat which includes a film-forming binder and an organic pigment or dye, an inorganic pigment, a metallic pigment, or a mixture thereof. The paint may also be a composition which comprises a primer in adhesion to a metal or plastic substrate; a pigmented base coat that is in adhesion to the primer, and which comprises a film-forming binder and an organic pigment or dye, an inorganic pigment, a metallic pigment, or a mixture thereof; and a clear top coat that is in adhesion to the base coat, and which comprises a film-forming binder and optionally a transparent pigment. The paint is preferably a topcoat for automobiles.
The invention furthermore relates to a process for stabilizing a coating based on organic polymers against damage by light, oxygen, and/or heat, which comprises mixing with the coating composition a mixture comprising one or more HALS of the present invention, as well as the use of mixtures comprising the one or more HALS of the present invention in coating compositions as stabilizers against damage by light, oxygen, and/or heat.
The coating compositions can comprise an organic solvent or solvent mixture in which the binder is soluble. The coating composition can otherwise be an aqueous solution or dispersion. The carrier can also be a mixture of organic solvent and water. The coating composition may be a high-solids paint or can be solvent-free (e.g., a powder coating material).
The pigments can be inorganic, organic or metallic pigments. The novel coating compositions preferably contain no pigments and preferably are used in clearcoat compositions.
Likewise preferred is the use of the coating composition as a topcoat for applications in the automobile industry, especially as a pigmented or unpigmented topcoat of the paint finish. Its use for underlying coats, however, is also possible.